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Chemistry: Atoms First

Paul Flowers, Edward J. Neth, William R. Robinson

Chapter 6

Composition of Substances and Solutions - all with Video Answers

Educators

Chapter Questions

02:03

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) $\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2}$

Ernest Williams
Ernest Williams
Numerade Educator
03:26

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) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}$

- -
- -
Numerade Educator
04:09

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 Williams
Ernest Williams
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Problem 4

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

Katherine Kartheiser
Katherine Kartheiser
Numerade Educator
04:36

Problem 4

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

- -
- -
Numerade Educator
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Problem 5

Determine the molecular mass of the following compounds:

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- -
Numerade Educator
01:09

Problem 6

Which molecule has a molecular mass of 28.05 amu?

Vysakh M
Vysakh M
Numerade Educator
00:51

Problem 7

What information is needed to determine the molecular formula of a compound from the empirical formula?

Lindsey Smaka
Lindsey Smaka
Numerade Educator
03:52

Problem 8

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," $\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}$
(c) the percent of calcium ion in $\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}$

Narayan Hari
Narayan Hari
Numerade Educator
05:18

Problem 9

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

Meg Jameson
Meg Jameson
Numerade Educator
01:37

Problem 10

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

Ernest Williams
Ernest Williams
Numerade Educator
01:16

Problem 11

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

Lindsey Smaka
Lindsey Smaka
Numerade Educator
04:08

Problem 12

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 Williams
Ernest Williams
Numerade Educator
05:56

Problem 13

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 $47.0 \% \mathrm{O}$

Catherine Lemar
Catherine Lemar
Numerade Educator
04:07

Problem 14

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 Williams
Ernest Williams
Numerade Educator
03:55

Problem 15

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

Rachel Vallejo
Rachel Vallejo
Numerade Educator
07:21

Problem 16

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 Williams
Ernest Williams
Numerade Educator
17:04

Problem 17

Polymers are large molecules composed of simple units repeated many times. Thus, they often have relatively simple empirical formulas. Calculate the empirical formulas of the following polymers:
(a) Lucite (Plexiglas); $59.9 \%$ 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; $86 \%$ C, $14 \%$ H
(d) polystyrene; $92.3 \% \mathrm{C}, 7.7 \% \mathrm{H}$
(e) Orlon; $67.9 \%$ C $, 5.70 \% \mathrm{H}, 26.4 \% \mathrm{~N}$

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
02:56

Problem 18

. A major textile dye manufacturer developed a new yellow dye. The dye has a percent composition of $75.95 \%$ 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.

Ronald Prasad
Ronald Prasad
Numerade Educator
02:00

Problem 19

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

Oluwapelumi Kolawole
Oluwapelumi Kolawole
Numerade Educator
00:51

Problem 20

What information is needed to calculate the molarity of a sulfuric acid solution?

Ernest Williams
Ernest Williams
Numerade Educator
03:15

Problem 21

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?

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
07:29

Problem 22

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) $0.2074 \mathrm{~g}$ 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) $7.0 \times 10^{-3} \mathrm{~mol}$ 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 Williams
Ernest Williams
Numerade Educator
05:49

Problem 23

Determine the molarity of each of the following solutions:
(a) $1.457 \mathrm{~mol} \mathrm{KCl}$ 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) $20.54 \mathrm{~g}$ of $\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}$ in $1575 \mathrm{~mL}$ 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

Catherine Lemar
Catherine Lemar
Numerade Educator
03:09

Problem 24

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.
(b) Answer the question.

Ernest Williams
Ernest Williams
Numerade Educator
06:00

Problem 25

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

Ali Daher
Ali Daher
Numerade Educator
06:55

Problem 26

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 $1.8 \times 10^{-6} \mathrm{M} \mathrm{FeSO}_{4}$, the minimum concentration of iron sulfate detectable by taste in drinking water

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
06:21

Problem 27

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

Catherine Lemar
Catherine Lemar
Numerade Educator
04:00

Problem 28

Consider this question: What is the molarity of $\mathrm{KMnO}_{4}$ 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.
(b) Answer the question.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
01:52

Problem 29

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

Catherine Lemar
Catherine Lemar
Numerade Educator
05:03

Problem 30

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) $1.49 \mathrm{~kg}$ of isopropyl alcohol, $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH},$ in $2.50 \mathrm{~L}$ 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 Williams
Ernest Williams
Numerade Educator
04:47

Problem 31

Calculate the molarity of each of the following solutions:
(a) 293 g HCl in $666 \mathrm{~mL}$ of solution, a concentrated $\mathrm{HCl}$ 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.

Catherine Lemar
Catherine Lemar
Numerade Educator
01:32

Problem 32

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 Williams
Ernest Williams
Numerade Educator
03:38

Problem 33

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

SO
Sofia Olsson
Numerade Educator
02:32

Problem 34

If $0.1718 \mathrm{~L}$ 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 Williams
Ernest Williams
Numerade Educator
02:12

Problem 35

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

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
02:32

Problem 36

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 Williams
Ernest Williams
Numerade Educator
01:26

Problem 37

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

Catherine Lemar
Catherine Lemar
Numerade Educator
05:47

Problem 38

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 $0.250-M$ 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) $2.35 \mathrm{~L}$ 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 $0.025-M$ solution of $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$ is diluted to $100.0 \mathrm{~mL}$

Ernest Williams
Ernest Williams
Numerade Educator
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Problem 39

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 $45.00 \mathrm{~mL} ?$

Ronald Prasad
Ronald Prasad
Numerade Educator
01:29

Problem 40

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 Williams
Ernest Williams
Numerade Educator
02:23

Problem 42

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 Williams
Ernest Williams
Numerade Educator
02:42

Problem 43

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?

Catherine Lemar
Catherine Lemar
Numerade Educator
02:52

Problem 44

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

Ernest Williams
Ernest Williams
Numerade Educator
01:12

Problem 45

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

Lindsey Smaka
Lindsey Smaka
Numerade Educator
04:01

Problem 46

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

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
01:13

Problem 47

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

Catherine Lemar
Catherine Lemar
Numerade Educator
04:19

Problem 48

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 $175 \mathrm{mg} \mathrm{CaCO}_{3} / \mathrm{L?}$

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
02:23

Problem 49

The level of mercury in a stream was suspected to be above the minimum considered safe (1 part per billion by weight). An analysis 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.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
05:44

Problem 50

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

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
03:35

Problem 51

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.

Catherine Lemar
Catherine Lemar
Numerade Educator
03:54

Problem 52

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

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
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Problem 53

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.

VP
Victoria Pacella
Numerade Educator
03:06

Problem 54

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 DSW is $1.029 \mathrm{~g} / \mathrm{mL}$, calculate the molarity of dextrose in the solution.

Ernest Williams
Ernest Williams
Numerade Educator
03:29

Problem 55

Find the molarity of a $40.0 \%$ by mass aqueous solution of sulfuric acid, $\mathrm{H}_{2} \mathrm{SO}_{4},$ for which the density is 1.3057 $\mathrm{g} / \mathrm{mL}$.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator