Q: Calculate the mass of PbI$$_2$$ produced when 0.010 mol Pb(NO$$_3$$)$$_2$$ reacts completely with excess NaI. (Molar mass of PbI$$_2 = 461.008 g/$$mol)

$$0.010 \times 461.008 = 4.61008 g$$

Q: If a reaction has a theoretical yield of 15.31 g and an actual yield of 13.11 g, what is the percent yield?

$$\frac{13.11}{15.31} \times 100 = 85.6\%$$

Question 1

When 0.020 mol NaI is mixed with 0.010 mol Pb(NO$$_3$$)$$_2$$, what is the limiting reactant?

Accepted Answer

Neither, they are perfectly matched

Question 2

Calculate the mass of PbI$$_2$$ produced when 0.010 mol Pb(NO$$_3$$)$$_2$$ reacts completely with excess NaI. (Molar mass of PbI$$_2 = 461.008 g/$$mol)

Accepted Answer

$$0.010 	imes 461.008 = 4.61008 g$$

Question 3

If 65 mL of 0.25 M NaI is mixed with 50 mL of 0.20 M Pb(NO$$_3$$)$$_2$$, what is the limiting reactant?

Accepted Answer

NaI

Question 4

What is the molarity of NO$$_3^-$$ ions in solution after the reaction between 0.01625 mol NaI and 0.0018125 mol Pb(NO$$_3$$)$$_2 in a $$total volume of 0.116 L?

Accepted Answer

$$\frac{0.018125}{0.116} = 0.156 M$$

Question 5

Which of the following best defines theoretical yield?

Accepted Answer

The maximum amount of product that can be formed from the given reactants

Question 6

If a reaction has a theoretical yield of 15.31 g and an actual yield of 13.11 g, what is the percent yield?

Accepted Answer

$$\frac{13.11}{15.31} 	imes 100 = 85.6\%$$

Question 7

In a reaction, increasing side reactions will ________ your theoretical yield.

Accepted Answer

decrease

Question 8

Chloe needs to produce 10.0 g of PCl$$_5$$ with an 86% yield. What mass of PCl$$_5$$ must be theoretically produced?

Accepted Answer

$$\frac{10.0}{0.86} = 11.63 g$$

Question 9

A student reacts FeBr$$_3$$ with Br$$_2 to $$produce Fe$$_3Br$_8. If $$the student wants to produce 250 g of Fe$$_3Br$_8$$, what is the first step in determining the amount of each reactant needed?

Accepted Answer

Calculate the moles of Fe$$_3Br$_8$$ using its molar mass

Question 10

Madeline reacts 6.13 g of K$$_2Cr$_2O$_7 ($$molar mass = 294.18 g/mol) with excess HCl. How many moles of K$$_2Cr$_2O$_7$$ are used?

Accepted Answer

$$\frac{6.13}{294.18} = 0.0208$$ mol

Question 11

In preparing a solution in a volumetric flask, why is it important that the meniscus just kisses the top of the line?

Accepted Answer

To ensure the correct volume is measured

Question 12

When dissolving a solid in a beaker before transferring to a volumetric flask, what is the purpose of swirling the solution?

Accepted Answer

To ensure complete dissolution of the solid

Question 13

If a solution is shaken after being transferred to a volumetric flask, what is happening?

Accepted Answer

Mixing the solution to ensure homogeneity

Question 14

Why is the line drawn on the skinny neck of a volumetric flask?

Accepted Answer

To allow for precise measurement of volume

Question 15

A reaction has a percent yield of 86%. If the theoretical yield is 0.05684 mol, how many moles are actually produced?

Accepted Answer

$$0.05684 	imes 0.86 = 0.04803$$ mol

Question 16

In a limiting reactant problem, which step should be performed first?

Accepted Answer

Calculate the moles of each reactant

Question 17

If 0.01425 mol NaI reacts with 0.005 mol Pb(NO$$_3$$)$$_2$$, what is the maximum number of moles of PbI$$_2$$ that can be formed?

Accepted Answer

0.005 mol

Question 18

Which of the following is a correct formula for calculating percent yield?

Accepted Answer

$$\frac{	ext{actual yield}}{	ext{theoretical yield}} 	imes 100$$

Stoichiometry, Limiting Reactants, and Solution Preparation in General Chemistry

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