Q: What is the formula for molarity ($$M$$)?

$$M = \dfrac{\text{moles of solute}}{\text{volume of solution in L}}$$

Question 1

Which statement best describes the purpose of a balanced chemical equation?

Accepted Answer

It shows the exact relationship between the amounts of reactants and products in moles.

Question 2

Octane ($$\mathrm{C_8H_{18}}) $$combusts according to the equation: $$2\mathrm{C_8H_{18}}(l) + 25\mathrm{O_2$}(g) \rightarrow 16\mathrm{CO_2$}(g) + 18\mathrm{H_2O}(g). If a 50.0 L $$gas tank contains 300. moles of octane, how many moles of $$\mathrm{CO_2$}$$ are produced when all the octane is burned?

Accepted Answer

$$2400 	ext{ moles}$$

Question 3

During photosynthesis, the reaction $$6\mathrm{CO_2$}(g) + 6\mathrm{H_2O}(l) \xrightarrow{sunlight} 6\mathrm{O_2$}(g) + \mathrm{C_6H_{12}O_6$}(aq)$$ occurs. If a plant consumes 37.8 g of $$\mathrm{CO_2$}$$, what mass of glucose ($$\mathrm{C_6H_{12}O_6$}) $$can be synthesized?

Accepted Answer

$$25.8 	ext{ g}$$

Question 4

A medium-sized home produces 16.0 kg of $$\mathrm{NO_2$}$$ annually. Given the reaction $$4\mathrm{NO_2$}(g) + \mathrm{O_2$}(g) + 2\mathrm{H_2O}(l) \rightarrow 4\mathrm{$$HNO_3$$}(aq)$$, what mass of $$\mathrm{$$HNO_3$$} is $$formed from this release of $$\mathrm{NO_2$}$$?

Accepted Answer

$$21.9 	ext{ kg}$$

Question 5

In the reaction $$4\mathrm{Na}(s) + \mathrm{O_2$}(g) \rightarrow 2\mathrm{Na_2O}(s)$$, if a flask contains 3 molecules of $$\mathrm{O_2$}$$, how many sodium atoms are required to react with all the oxygen?

Accepted Answer

12 sodium atoms

Question 6

You have 6 graham crackers, 3 marshmallows, and 4 chocolate squares. According to the s'mores 'reaction' (1 graham cracker + 1 marshmallow + 1 chocolate square $$\rightarrow 1 s$$'more), which ingredient is the limiting reactant?

Accepted Answer

Marshmallows

Question 7

Given the s'mores 'reaction' (1 graham cracker + 1 marshmallow + 1 chocolate square $$\rightarrow 1 s$$'more), how many s'mores can you make with 6 graham crackers, 3 marshmallows, and 4 chocolate squares?

Accepted Answer

3

Question 8

For the reaction $$\mathrm{N_2$}(g) + 3\mathrm{H_2$}(g) \rightarrow 2\mathrm{NH_3$}(g)$$, if a flask initially contains 2 molecules of $$\mathrm{N_2$}$$ and 6 molecules of $$\mathrm{H_2$}$$, what will be present after the reaction is complete?

Accepted Answer

4 molecules of $$\mathrm{NH_3$}$$, no $$\mathrm{N_2$} or$$ $$\mathrm{H_2$}$$ left

Question 9

Magnesium reacts with oxygen: $$2\mathrm{Mg}(s) + \mathrm{O_2$}(g) \rightarrow 2\mathrm{MgO}(s). If a $$mixture contains 42.5 g Mg and 33.8 g $$\mathrm{O_2$}$$, what is the limiting reagent?

Accepted Answer

$$\mathrm{Mg}$$

Question 10

Using the previous reaction ($$2\mathrm{Mg}(s) + \mathrm{O_2$}(g) \rightarrow 2\mathrm{MgO}(s)$$), what is the theoretical yield of $$\mathrm{MgO} in $$grams if the limiting reagent is 42.5 g Mg?

Accepted Answer

$$69.9 	ext{ g}$$

Question 11

If the actual yield of $$\mathrm{MgO} in $$the previous reaction is 55.9 g, what is the percent yield?

Accepted Answer

$$80.0\%$$

Question 12

For the reaction $$3\mathrm{NO_2$}(g) + \mathrm{H_2O}(l) \rightarrow 2\mathrm{$$HNO_3$$}(l) + \mathrm{NO}(g)$$, if 5 moles of $$\mathrm{NO_2$}$$ react with 1 mole of water, how many moles of the excess reagent remain after the reaction?

Accepted Answer

2 mol

Question 13

Which of the following best defines a solution in chemistry?

Accepted Answer

A homogeneous mixture of two or more pure substances

Question 14

Which statement correctly describes a concentrated solution?

Accepted Answer

It contains a large quantity of solute relative to the amount of solvent.

Question 15

What is the formula for molarity ($$M$$)?

Accepted Answer

$$M = \dfrac{	ext{moles of solute}}{	ext{volume of solution in L}}$$

Question 16

Which equation is used to calculate the dilution of solutions?

Accepted Answer

$$M_1V_1 = M_2V_2$$

Question 17

Molality ($$m) is $$defined as:

Accepted Answer

Moles of solute per kilogram of solvent

Question 18

How many liters of a $$0.125\ \mathrm{mol\ L$$^{-1}$$}$$ NaOH solution contains $$0.255$$ mol NaOH?

Accepted Answer

$$2.04\ \mathrm{L}$$

Question 19

To what volume should you dilute $$0.200\ \mathrm{L} of a$$ $$15.0\ \mathrm{M}$$ NaOH solution to obtain a $$3.00\ \mathrm{M}$$ NaOH solution?

Accepted Answer

$$1.00\ \mathrm{L}$$

Question 20

What volume of a $$0.150\ \mathrm{M}$$ KCl solution will completely react with $$0.150\ \mathrm{L} of a$$ $$0.175\ \mathrm{M} Pb(NO$_3$$)$$_2$$ solution according to the reaction $$2\mathrm{KCl}(aq) + \mathrm{Pb(NO_3$)_2}(aq) \rightarrow \mathrm{$$PbCl_2$$}(s) + 2\mathrm{$$KNO_3$$}(aq)$$?

Accepted Answer

$$0.350\ \mathrm{L}$$

Chapter 4 – Reaction Stoichiometry & Solution Chemistry: Study Notes

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