# Chemistry

## Educators

Problem 1

What is the total mass (amu) of carbon in each of the following molecules?
(a) $\mathrm{CH}_{4}$
(b) $\mathrm{CHCl}_{3}$
(c) $\mathrm{C}_{12} \mathrm{H}_{10} \mathrm{O}_{6}$
(d) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}$

Ernest W.

Problem 2

What is the total mass of hydrogen in each of the molecules?
(a) $\mathrm{CH}_{4}$
(b) $\mathrm{CHCl}_{3}$
(c) $\mathrm{C}_{12} \mathrm{H}_{10} \mathrm{O}_{6}$
(d) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}$

Emily P.

Problem 3

Calculate the molecular or formula mass of each of the following:
(a) $\mathrm{P}_{4}$
(b) $\mathrm{H}_{2} \mathrm{O}$
(c) $\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}$
(d) $\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}$ (acetic acid)
(e) $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$ (sucrose, cane sugar).

Ernest W.

Problem 4

Determine the molecular mass of the following compounds:
a)
b)
c)
d)

Emily P.

Problem 5

Determine the molecular mass of the following compounds:
a)
b)
c)
d)

Ernest W.

Problem 6

Which molecule has a molecular mass of 28.05 amu?
a)
b)
c)

Emily P.

Problem 7

Write a sentence that describes how to determine the number of moles of a compound in a known mass of the compound if we know its molecular formula.

Ernest W.

Problem 8

Compare 1 mole of $\mathrm{H}_{2}, 1$ mole of $\mathrm{O}_{2},$ and 1 mole of $\mathrm{F}_{2}$
(a) Which has the largest number of molecules? Explain why.
(b) Which has the greatest mass? Explain why.

Emily P.

Problem 9

Which contains the greatest mass of oxygen: 0.75 mol of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right), 0.60 \mathrm{mol}$ of formic acid (HCO_{2} \mathrm { H } ) $,$ or 1.0 $\mathrm{mol}$ of water $\left(\mathrm{H}_{2} \mathrm{O}\right) ?$ Explain why.

Ernest W.

Problem 10

Which contains the greatest number of moles of moles of oxygen atoms: 1 mol of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right), 1 \mathrm{mol}$ of formic acid $\left(\mathrm{HCO}_{2} \mathrm{H}\right)$ , or 1 $\mathrm{mol}$ of water $\left(\mathrm{H}_{2} \mathrm{O}\right) ?$ Explain why.

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Problem 11

How are the molecular mass and the molar mass of a compound similar and how are they different?

Ernest W.

Problem 12

Calculate the molar mass of each of the following compounds:
(a) hydrogen fluoride, HF
(b) ammonia, $\mathrm{NH}_{3}$
(c) nitric acid, HNO_ $_{3}$
(d) silver sulfate, $\mathrm{Ag}_{2} \mathrm{SO}_{4}$
(e) boric acid, $\mathrm{B}(\mathrm{OH})_{3}$

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Problem 13

Calculate the molar mass of each of the following:
(a) $\mathrm{S}_{8}$
(b) $\mathrm{C}_{5} \mathrm{H}_{12}$
(c) $\mathrm{Sc}_{2}\left(\mathrm{SO}_{4}\right)_{3}$
(d) $\mathrm{CH}_{3} \mathrm{COCH}_{3}$ (acetone)
(e) $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(\text { glucose })$

Ernest W.

Problem 14

Calculate the empirical or molecular formula mass and the molar mass of each of the following minerals:
(a) limestone, $\mathrm{CaCO}_{3}$
(b) halite, NaCl
(c) beryl, Be_lz $\mathrm{Al}_{2} \mathrm{Si}_{6} \mathrm{O}_{18}$
(d) malachite, $\mathrm{Cu}_{2}(\mathrm{OH})_{2} \mathrm{CO}_{3}$
(e) turquoise, CuAl_ $\left(\mathrm{PO}_{4}\right)_{4}(\mathrm{OH})_{8}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}$

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Problem 15

Calculate the molar mass of each of the following:
(a) the anesthetic halothane, $\mathrm{C}_{2} \mathrm{HBrClF}_{3}$
(b) the herbicide paraquat, $\mathrm{C}_{12} \mathrm{H}_{14} \mathrm{N}_{2} \mathrm{Cl}_{2}$
(c) caffeine, $\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{N}_{4} \mathrm{O}_{2}$
(d) urea, $\mathrm{CO}\left(\mathrm{NH}_{2}\right)_{2}$
(e) a typical soap, $\mathrm{C}_{17} \mathrm{H}_{35} \mathrm{CO}_{2} \mathrm{Na}$

Ernest W.

Problem 16

Determine the number of moles of compound and the number of moles of each type of atom in each of the following:
(a) 25.0 g of propylene, $\mathrm{C}_{3} \mathrm{H}_{6}$
(b) $3.06 \times 10^{-3} \mathrm{g}$ of the amino acid glycine, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NO}_{2}$
(c) 25 $\mathrm{lb}$ of the herbicide Treflan, $\mathrm{C}_{13} \mathrm{H}_{16} \mathrm{N}_{2} \mathrm{O}_{4} \mathrm{F}(1 \mathrm{lb}=454 \mathrm{g})$
(d) 0.125 $\mathrm{kg}$ of the insecticide Paris Green, $\mathrm{Cu}_{4}\left(\mathrm{AsO}_{3}\right)_{2}\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2}$
(e) 325 $\mathrm{mg}$ of aspirin, $\mathrm{C}_{6} \mathrm{H}_{4}\left(\mathrm{CO}_{2} \mathrm{H}\right)\left(\mathrm{CO}_{2} \mathrm{CH}_{3}\right)$

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Problem 17

Determine the mass of each of the following:
(a) 0.0146 $\mathrm{mol} \mathrm{KOH}$
(b) 10.2 $\mathrm{mol}$ ethane, $\mathrm{C}_{2} \mathrm{H}_{6}$
(c) $1.6 \times 10^{-3} \mathrm{mol} \mathrm{Na}_{2} \mathrm{SO}_{4}$
(d) $6.854 \times 10^{3} \mathrm{mol}$ glucose, $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$
(e) 2.86 $\mathrm{mol} \mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6} \mathrm{Cl}_{3}$

Ernest W.

Problem 18

Determine the number of moles of the compound and determine the number of moles of each type of atom in each of the following:
(a) 2.12 g of potassium bromide, KBr
(b) 0.1488 g of phosphoric acid, $\mathrm{H}_{3} \mathrm{PO}_{4}$
(c) 23 $\mathrm{kg}$ of calcium carbonate, $\mathrm{CaCO}_{3}$
(d) 78.452 $\mathrm{g}$ of aluminum sulfate, $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$
(e) 0.1250 $\mathrm{mg}$ of caffeine, $\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{N}_{4} \mathrm{O}_{2}$

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Problem 19

Determine the mass of each of the following:
(a) 2.345 mol LiCl
(b) 0.0872 mol acetylene, $\mathrm{C}_{2} \mathrm{H}_{2}$
(c) $3.3 \times 10^{-2} \mathrm{mol} \mathrm{Na}_{2} \mathrm{CO}_{3}$
(d) $1.23 \times 10^{3} \mathrm{mol}$ fructose, $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$
(e) 0.5758 $\mathrm{mol} \mathrm{FeSO}_{4}\left(\mathrm{H}_{2} \mathrm{O}\right)_{7}$

Ernest W.

Problem 20

The approximate minimum daily dietary requirement of the amino acid leucine, $C_{6} \mathrm{H}_{13} \mathrm{NO}_{2},$ is 1.1 $\mathrm{g}$ . What is this requirement in moles?

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Problem 21

Determine the mass in grams of each of the following:
(a) 0.600 mol of oxygen atoms
(b) 0.600 mol of oxygen molecules, $\mathrm{O}_{2}$
(c) 0.600 mol of ozone molecules, $\mathrm{O}_{3}$

Ernest W.

Problem 22

A $55-$ -kg woman has $7.5 \times 10^{-3}$ mol of hemoglobin (molar mass $=64,456 \mathrm{g} / \mathrm{mol} )$ in her blood. How many hemoglobin molecules is this? What is this quantity in grams?

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Problem 23

Determine the number of atoms and the mass of zirconium, silicon, and oxygen found in 0.3384 mol of zircon, Zrsio_, a semiprecious stone.

Ernest W.

Problem 24

Determine which of the following contains the greatest mass of hydrogen: 1 $\mathrm{mol}$ of $\mathrm{CH}_{4}, 0.6 \mathrm{mol}$ of $\mathrm{C}_{6} \mathrm{H}_{6},$ or 0.4 $\mathrm{mol}$ of $\mathrm{C}_{3} \mathrm{H}_{8}$ .

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Problem 25

Determine which of the following contains the greatest mass of aluminum: 122 $\mathrm{g}$ of AlPO $_{4}, 266 \mathrm{g}$ of $\mathrm{Al}_{2} \mathrm{C} 1_{6},$ or 225 $\mathrm{g}$ of $\mathrm{Al}_{2} \mathrm{S}_{3}$ .

Ernest W.

Problem 26

Diamond is one form of elemental carbon. An engagement ring contains a diamond weighing 1.25 carats $(1$ carat $=200 \mathrm{mg}$ ). How many atoms are present in the diamond?

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Problem 27

The Cullinan diamond was the largest natural diamond ever found (January $25,1905 ) .$ It weighed 3104 carats $(1 \text { carat }=200 \mathrm{mg}) .$ How many carbon atoms were present in the stone?

Ernest W.

Problem 28

One 55 -gram serving of a particular cereal supplies 270 $\mathrm{mg}$ of sodium, 11$\%$ of the recommended daily allowance. How many moles and atoms of sodium are in the recommended daily allowance?

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Problem 29

A certain nut crunch cereal contains 11.0 grams of sugar (sucrose, $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11} )$ per serving size of 60.0 $\mathrm{grams}$ . How many servings of this cereal must be eaten to consume 0.0278 moles of sugar?

Ernest W.

Problem 30

A tube of toothpaste contains 0.76 $\mathrm{g}$ of sodium monofluorophosphate $\left(\mathrm{Na}_{2} \mathrm{PO}_{3} \mathrm{F}\right)$ in 100 $\mathrm{mL}$
(a) What mass of fluorine atoms in mg was present?
(b) How many fluorine atoms were present?

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Problem 31

Which of the following represents the least number of molecules?
(a) 20.0 g of $\mathrm{H}_{2} \mathrm{O}(18.02 \mathrm{g} / \mathrm{mol})$
(b) 77.0 $\mathrm{g}$ of $\mathrm{CH}_{4}(16.06 \mathrm{g} / \mathrm{mol})$
(c) 68.0 $\mathrm{g}$ of $\mathrm{CaH}_{2}(42.09 \mathrm{g} / \mathrm{mol})$
(d) 100.0 $\mathrm{g}$ of $\mathrm{N}_{2} \mathrm{O}(44.02 \mathrm{g} / \mathrm{mol})$
(e) 84.0 $\mathrm{g}$ of $\mathrm{HF}(20.01 \mathrm{g} / \mathrm{mol})$

Ernest W.

Problem 32

What information do we need to determine the molecular formula of a compound from the empirical formula?

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Problem 33

Calculate the following to four significant figures:
(a) the percent composition of ammonia, $\mathrm{NH}_{3}$
(b) the percent composition of photographic fixer solution ( "hypo"), Na_{2} \mathrm { S } _ { 2 } \mathrm { O } _ { 3 }
(c) the percent of calcium ion in $\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}$

Ernest W.

Problem 34

Determine the following to four significant figures:
(a) the percent composition of hydrazoic acid, HN_{3}
(b) the percent composition of TNT, $\mathrm{C}_{6} \mathrm{H}_{2}\left(\mathrm{CH}_{3}\right)\left(\mathrm{NO}_{2}\right)_{3}$
(c) the percent of $\mathrm{SO}_{4}^{2-}$ in $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$

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Problem 35

Determine the percent ammonia, $\mathrm{NH}_{3},$ in $\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6} \mathrm{Cl}_{3},$ to three significant figures.

Ernest W.

Problem 36

Determine the percent water in $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$ to three significant figures.

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Problem 37

Determine the empirical formulas for compounds with the following percent compositions:
(a) 15.8$\%$ carbon and 84.2$\%$ sulfur
(b) 40.0$\%$ carbon, 6.7$\%$ hydrogen, and 53.3$\%$ oxygen

Ernest W.

Problem 38

Determine the empirical formulas for compounds with the following percent compositions:
(a) 43.6$\%$ phosphorus and 56.4$\%$ oxygen
(b) $28.7 \% \mathrm{K}, 1.5 \% \mathrm{H}, 22.8 \% \mathrm{P},$ and 47.0$\% \mathrm{O}$

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Problem 39

A compound of carbon and hydrogen contains 92.3$\% \mathrm{C}$ and has a molar mass of 78.1 $\mathrm{g} / \mathrm{mol}$ . What is its molecular formula?

Ernest W.

Problem 40

Dichloroethane, a compound that is often used for dry cleaning, carbon, hydrogen, and chlorine. It has a molar mass of 99 g/mol. Analysis of a sample shows that it contains 24.3$\%$ carbon and 4.1$\%$ hydrogen. What is its molecular formula?

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Problem 41

Determine the empirical and molecular formula for chrysotile asbestos. Chrysotile has the following percent composition: $28.03 \% \mathrm{Mg}, 21.60 \% \mathrm{Si}, 1.16 \% \mathrm{H},$ and 49.21$\% \mathrm{O}$ . The molar mass for chrysotile is 520.8 $\mathrm{g} / \mathrm{mol}$ .

Ernest W.

Problem 42

Polymers are large molecules composed of simple units repeated many times. They often have relatively simple empirical formulas. Calculate the empirical formulas of the following polymers:
(a) Lucite (Plexiglas); $59.9 \% \mathrm{C}, 8.06 \% \mathrm{H}, 32.0 \% \mathrm{O}$
(b) Saran; $24.8 \% \mathrm{C}, 2.0 \% \mathrm{H}, 73.1 \% \mathrm{Cl}$
(c) polyethylene; $86 \% \mathrm{C}, 14 \% \mathrm{H}$
(d) polystyrene; $92.3 \% \mathrm{C}, 7.7 \% \mathrm{H}$
(e) Orlon; $67.9 \% \mathrm{C}, 5.70 \% \mathrm{H}, 26.4 \% \mathrm{N}$

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Problem 43

A major textile dye manufacturer developed a new yellow dye has a percent composition of 75.95$\%$
$\mathrm{C}, 17.72 \% \mathrm{N},$ and 6.33$\% \mathrm{H}$ by mass with a molar mass of about 240 $\mathrm{g} / \mathrm{mol}$ . Determine the molecular formula of the dye.

Ernest W.

Problem 44

Explain what changes and what stays the same when 1.00 $\mathrm{L}$ of a solution of $\mathrm{NaCl}$ is diluted to 1.80 $\mathrm{L}$ .

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Problem 45

What information do we need to calculate the molarity of a sulfuric acid solution?

Ernest W.

Problem 46

What does it mean when we say that a 200 -mL sample and a 400 -mL sample of a solution of salt have the same molarity? In what ways are the two samples identical? In what ways are these two samples different?

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Problem 47

Determine the molarity for each of the following solutions:
(a) 0.444 $\mathrm{mol}$ of $\mathrm{CoCl}_{2}$ in 0.654 $\mathrm{L}$ of solution
(b) 98.0 $\mathrm{g}$ of phosphoric acid, $\mathrm{H}_{3} \mathrm{PO}_{4},$ in 1.00 $\mathrm{L}$ of solution
(c) 0.2074 g of calcium hydroxide, $\mathrm{Ca}(\mathrm{OH})_{2},$ in 40.00 $\mathrm{mL}$ of solution
(d) 10.5 $\mathrm{kg}$ of $\mathrm{Na}_{2} \mathrm{SO}_{4} \cdot 10 \mathrm{H}_{2} \mathrm{O}$ in 18.60 $\mathrm{L}$ of solution
(e) $7.0 \times 10^{-3}$ mol of $\mathrm{I}_{2}$ in 100.0 $\mathrm{mL}$ of solution
(f) $1.8 \times 10^{4} \mathrm{mg}$ of $\mathrm{HCl}$ in 0.075 $\mathrm{L}$ of solution

Ernest W.

Problem 48

Determine the molarity of each of the following solutions:
(a) 1.457 mol $\mathrm{KCl}$ in 1.500 $\mathrm{L}$ of solution
(b) 0.515 $\mathrm{g}$ of $\mathrm{H}_{2} \mathrm{SO}_{4}$ in 1.00 $\mathrm{L}$ of solution
(c) 20.54 g of $\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}$ in 1575 mL of solution
(d) 2.76 $\mathrm{kg}$ of $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$ in 1.45 $\mathrm{L}$ of solution
(e) 0.005653 $\mathrm{mol}$ of $\mathrm{Br}_{2}$ in 10.00 $\mathrm{mL}$ of solution
(f) 0.000889 $\mathrm{g}$ of glycine, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NO}_{2},$ in 1.05 $\mathrm{mL}$ of solution

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Problem 49

Consider this question: What is the mass of the solute in 0.500 $\mathrm{L}$ of 0.30 $\mathrm{M}$ glucose, $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6},$ used for
intravenous injection?
(a) Outline the steps necessary to answer the question.

Ernest W.

Problem 50

Consider this question: What is the mass of solute in 200.0 $\mathrm{L}$ of a $1.556-M$ solution of KBr?
(a) Outline the steps necessary to answer the question.

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Problem 51

Calculate the number of moles and the mass of the solute in each of the following solutions:
(a) 2.00 $\mathrm{L}$ of $18.5 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4},$ concentrated sulfuric acid
(b) 100.0 $\mathrm{mL}$ of $3.8 \times 10^{-5} \mathrm{M} \mathrm{NaCN}$ , the minimum lethal concentration of sodium cyanide in blood serum
(c) 5.50 $\mathrm{L}$ of 13.3 $\mathrm{M} \mathrm{H}_{2} \mathrm{CO}$ , the formaldehyde used to "fix" tissue samples
(d) 325 $\mathrm{mL}$ of $1.8 \times 10^{-6} \mathrm{M}$ Feso $_{4},$ the minimum concentration of iron sulfable by taste in drinking water

Ernest W.

Problem 52

Calculate the number of moles and the mass of the solute in each of the following solutions:
(a) 325 $\mathrm{mL}$ of $8.23 \times 10^{-5} \mathrm{M} \mathrm{KI}$ , a source of iodine in the diet
(b) 75.0 $\mathrm{mL}$ of $2.2 \times 10^{-5} \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4},$ a sample of acid rain
(c) 0.2500 $\mathrm{L}$ of $0.1135 \mathrm{M} \mathrm{K}_{2} \mathrm{CrO}_{4},$ an analytical reagent used in iron assays
(d) 10.5 $\mathrm{L}$ of $3.716 \mathrm{M}\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4},$ a liquid fertilizer

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Problem 53

Consider this question: What is the molarity of KMnO_ in a solution of 0.0908 $\mathrm{g}$ of $\mathrm{KMnO}_{4}$ in 0.500 $\mathrm{L}$ of solution?
(a) Outline the steps necessary to answer the question.

Ernest W.

Problem 54

Consider this question: What is the molarity of HCl if 35.23 $\mathrm{mL}$ of a solution of a solution of $\mathrm{HCl}$ contain 0.3366 $\mathrm{g}$ of HCl?
(a) Outline the steps necessary to answer the question.

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Problem 55

Calculate the molarity of each of the following solutions:
(a) 0.195 g of cholesterol, $\mathrm{C}_{27} \mathrm{H}_{46} \mathrm{O}$ , in 0.100 $\mathrm{L}$ of serum, the average concentration of cholesterol in human serum
(b) 4.25 $\mathrm{g}$ of $\mathrm{NH}_{3}$ in 0.500 $\mathrm{L}$ of solution, the concentration of $\mathrm{NH}_{3}$ in household ammonia
(c) 1.49 kg of isopropyl alcohol, $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}$ , in 2.50 L of solution, the concentration of isopropyl alcohol in rubbing alcohol
(d) 0.029 $\mathrm{g}$ of $\mathrm{I}_{2}$ in 0.100 $\mathrm{L}$ of solution, the solubility of $\mathrm{I}_{2}$ in water at $20^{\circ} \mathrm{C}$

Ernest W.

Problem 56

Calculate the molarity of each of the following solutions:
(a) 293 $\mathrm{g} \mathrm{HCl}$ in 666 $\mathrm{mL}$ of solution, a concentrated HCl solution
(b) 2.026 $\mathrm{g} \mathrm{FeCl}_{3}$ in 0.1250 $\mathrm{L}$ of a solution used as an unknown in general chemistry laboratories
(c) 0.001 $\mathrm{mg} \mathrm{Cd}^{2+}$ in $0.100 \mathrm{L},$ the maximum permissible concentration of cadmium in drinking water
(d) 0.0079 $\mathrm{g} \mathrm{C}_{7} \mathrm{H}_{5} \mathrm{SNO}_{3}$ in one ounce ( 29.6 $\mathrm{mL} )$ , the concentration of saccharin in a diet soft drink.

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Problem 57

There is about 1.0 $\mathrm{g}$ of calcium, as $\mathrm{Ca}^{2+},$ in 1.0 $\mathrm{L}$ of milk. What is the molarity of $\mathrm{Ca}^{2+}$ in milk?

Ernest W.

Problem 58

What volume of a $1.00-M \mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3}$ solution can be diluted to prepare 1.00 $\mathrm{L}$ of a solution with a concentration of 0.250 $\mathrm{M}$ ?

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Problem 59

If 0.1718 L of a $0.3556-M \mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}$ solution is diluted to a concentration of $0.1222 \mathrm{M},$ what is the volume of the resulting solution?

Ernest W.

Problem 60

If 4.12 Lof a $0.850 M-\mathrm{H}_{3} \mathrm{PO}_{4}$ solution is be diluted to a volume of $10.00 \mathrm{L},$ what is the concentration of the resulting solution?

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Problem 61

What volume of a $0.33-M \mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$ solution can be diluted to prepare 25 $\mathrm{mL}$ of a solution with a concentration of 0.025 $\mathrm{M}$ ?

Ernest W.

Problem 62

What is the concentration of the NaCl solution that results when 0.150 $\mathrm{L}$ of a $0.556-\mathrm{M}$ solution is allowed to evaporate until the volume is reduced to 0.105 $\mathrm{L}$ ?

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Problem 63

What is the molarity of the diluted solution when each of the following solutions is diluted to the given final volume?
(a) 1.00 $\mathrm{L}$ of a $0.250-\mathrm{M}$ solution of $\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3}$ is diluted to a final volume of 2.00 $\mathrm{L}$
(b) 0.5000 $\mathrm{L}$ of a $0.1222-M$ solution of $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}$ is diluted to a final volume of 1.250 $\mathrm{L}$
(c) 2.35 L of a $0.350-$ M solution of $\mathrm{H}_{3} \mathrm{PO}_{4}$ is diluted to a final volume of 4.00 $\mathrm{L}$
(d) 22.50 $\mathrm{mL}$ of a $0.025-\mathrm{M}$ solution of $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$ is diluted to 100.0 $\mathrm{mL}$

Ernest W.

Problem 64

What is the final concentration of the solution produced when 225.5 $\mathrm{mL}$ of a 0.09988 -M solution of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ is allowed to evaporate until the solution volume is reduced to 45.00 $\mathrm{mL}$ ?

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Problem 65

A 2.00 -L bottle of a solution of concentrated HCl was purchased for the general chemistry laboratory. The solution contained 868.8 $\mathrm{g}$ of $\mathrm{HCl}$ . What is the molarity of the solution?

Ernest W.

Problem 66

An experiment in a general chemistry laboratory calls for a $2.00-M$ solution of HCl. How many mL of 11.9 $\mathrm{M}$ HCl would be required to make 250 $\mathrm{mL}$ of 2.00 $\mathrm{M}$ HCl?

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Problem 67

What volume of a $0.20-M \mathrm{K}_{2} \mathrm{SO}_{4}$ solution contains 57 $\mathrm{g}$ of $\mathrm{K}_{2} \mathrm{SO}_{4} ?$

Ernest W.

Problem 68

The US Environmental Protection Agency (EPA) places limits on the quantities of toxic substances that may be discharged into the sewer system. Limits have been established for a variety of substances, including hexavalent chromium, which is limited to 0.50 $\mathrm{mg} / \mathrm{L}$ . If an industry is discharging hexavalent chromium as potassium dichromate $\left(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\right),$ what is the maximum permissible molarity of that substance?

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Problem 69

Consider this question: What mass of a concentrated solution of nitric acid $\left(68.0 \% \mathrm{HNO}_{3} \text { by mass ) is needed to }\right.$ prepare 400.0 g of a 10.0$\%$ solution of $\mathrm{HNO}_{3}$ by mass?
(a) Outline the steps necessary to answer the question.

Ernest W.

Problem 70

What mass of a 4.00$\%$ NaOH solution by mass contains 15.0 $\mathrm{g}$ of $\mathrm{NaOH}$ ?

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Problem 71

What mass of solid NaOH $(97.0 \% \mathrm{NaOH} \text { by mass) is required to prepare } 1.00 \mathrm{L} \text { of a } 10.0 \% \text { solution of } \mathrm{NaOH}$ by mass? The density of the 10.0$\%$ solution is 1.109 $\mathrm{g} / \mathrm{mL}$ .

Ernest W.

Problem 72

What mass of HCl is contained in 45.0 mL of an aqueous HCl solution that has a density of 1.19 $\mathrm{cm}^{-3}$ and contains 37.21$\%$ HCl by mass?

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Problem 73

The hardness of water (hardness count) is usually expressed in parts per million (by mass) of $\mathrm{CaCO}_{3},$ which is equivalent to milligrams of $\mathrm{CaCO}_{3}$ per liter of water. What is the molar concentration of $\mathrm{Ca}^{2+}$ ions in a water sample with a hardness count of 175 $\mathrm{mg} \mathrm{CaCO}_{3} \mathrm{L}$ ?

Ernest W.

Problem 74

The level of mercury in a stream was suspected to be above the minimum considered safe ( 1 part per billion by weight). An andysis indicated that the concentration was 0.68 parts per billion. Assume a density of 1.0 $\mathrm{g} / \mathrm{mL}$ and calculate the molarity of mercury in the stream.

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Problem 75

In Canada and the United Kingdom, devices that measure blood glucose levels provide a reading in millimoles per liter. If a measurement of 5.3 $\mathrm{mM}$ is observed, what is the concentration of glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ in mildL?

Ernest W.

Problem 76

A throat spray is 1.40$\%$ by mass phenol, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}$ , in water. If the solution has a density of 0.9956 $\mathrm{g} / \mathrm{mL}$ , calculate the molarity of the solution.

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Problem 77

Copper(I) iodide (Cul) is often added to table salt as a dietary source of iodine. How many moles of Cul are contained in 1.00 $\mathrm{lb}(454 \mathrm{g})$ of table salt containing 0.0100$\%$ Cul by mass?

Ernest W.

Problem 78

A cough syrup contains 5.0$\%$ ethyl alcohol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH},$ by mass. If the density of the solution is 0.9928 $\mathrm{g} / \mathrm{mL}$ , determine the molarity of the alcohol in the cough syrup.

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Problem 79

D5W is a solution used as an intravenous fluid. It is a 5.0$\%$ by mass solution of dextrose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ in water. If the density of D5W is 1.029 $\mathrm{g} / \mathrm{mL}$ , calculate the molarity of dextrose in the solution.

Ernest W.
Find the molarity of a 40.0$\%$ by mass aqueous solution of sulfuric acid, for which the density is 1.3057 $\mathrm{g} / \mathrm{mL}$ .