For each of the following solutions, the mass of solute is...

For each of the following solutions, the mass of solute is given, followed by the total volume of the solution prepared. Calculate the molarity of each solution. a. 5.59 g $\mathrm{CaCl}_{2} ; 125 \mathrm{mL}$ b. 2.34 g $\mathrm{CaCl}_{2} ; 125 \mathrm{mL}$ c. 8.73 g $\mathrm{CaCl}_{2} ; 125 \mathrm{mL}$ d. 11.5 g $\mathrm{CaCl}_{2} ; 125 \mathrm{mL}$

For each of the following solutions, the mass of solute is given, followed by the total volume of the solution prepared. Calculate the molarity of each solution.
a. 5.59 g $\mathrm{CaCl}_{2} ; 125 \mathrm{mL}$
b. 2.34 g $\mathrm{CaCl}_{2} ; 125 \mathrm{mL}$
c. 8.73 g $\mathrm{CaCl}_{2} ; 125 \mathrm{mL}$
d. 11.5 g $\mathrm{CaCl}_{2} ; 125 \mathrm{mL}$

Key Concepts

Molarity

Molarity is a measure of the concentration of a solute in a solution, defined as the number of moles of the solute dissolved per liter of the solution. It is a central concept in solution chemistry and is used to express how concentrated a solution is.

Moles

Moles are a unit that quantifies the amount of substance, representing 6.022 x 10^23 units of that substance. Converting the mass of a solute to moles by using its molar mass is a fundamental step in calculating molarity.

Molar Mass

Molar mass is the mass of one mole of a substance, commonly expressed in grams per mole (g/mol). It allows for the conversion between the mass of a substance and the number of moles, which is essential for quantitative chemical calculations.

Unit Conversion

Unit conversion is a key skill in chemistry that involves converting quantities from one unit to another, such as milliliters to liters when calculating molarity. Ensuring that units are consistent is critical in performing accurate calculations.

Transcript

00:01 So for this question, we are given the mass of the solute and the total volume of solution.

00:08 So in this case, the solute is the cacl2 for calcium chloride.

00:13 And with this information, we have to find the molarity.

00:16 So i've written out what we have on the left here.

00:20 So let's start with part a.

00:21 We have 5 .59 grams calcium chloride and 125 milliliters of solution.

00:27 So first we have to convert this to liters.

00:31 Which is 0 .125 liters.

00:34 And this is because when we use the equation to solve for moles, c equals n over v or concentration is moles over volume.

00:44 The units have to be in liters.

00:47 And we're going to find moles so that we can eventually find the molarity.

00:58 But first, we have volume, but we don't have the moles.

01:02 So we can use the mass given to eventually use this equation to find the concentration.

01:13 So to find the moles, moles is equal to mass divided by molar mass.

01:21 And the mass of calcium chloride is 5 .59 grams.

01:30 And the molar mass is 110 .9 grams per mole.

01:38 And i got this number as i added up the molar mass of one calcium and two chlorines.

01:49 And those masses can be found on your periodic table.

01:55 So this 5 .59 grams divided by 110 .9 grams per mole gives us 0 .0, about 0 .0504 moles.

02:10 Now that we have moles and we have our volume converted, we can solve for concentration or molarity.

02:26 It is the same thing.

02:28 So concentration is moles, which is 0 .0504 divided by volume, which is 0 .125 liters.

02:55 And this gives us, after we round, 0 .025 liters.

02:58 And this gives us, after we round, 0 .0 .5.

03:00 For 0 .03 molars.

03:07 So that is our molarity.

03:12 And i'm going to do the same thing for part b.

03:15 First, i'm going to convert this into liters by dividing by 1 ,000...

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