Q: Which of the following pairs of reactants will result in a precipitation reaction?

$$\text{Na}_2\text{SO}_4(aq) + \text{Ba(NO}_3)_2(aq)$$

Question 1

Which of the following gases is NOT a major contributor to global warming?

Accepted Answer

Argon

Question 2

According to the balanced reaction $$3 	ext{NO}_2(g) + 	ext{H}_2	ext{O}(l) ightarrow 2 	ext{HNO}_3(aq) + 	ext{NO}(g)$$, how many moles of $$	ext{HNO}_3$$ are formed from 3.75 moles of $$	ext{NO}_2 if $$there is plenty of water present?

Accepted Answer

$$2.50$$ mol

Question 3

Magnesium burns in air with a dazzling brilliance to produce magnesium oxide: $$2 	ext{Mg}(s) + 	ext{O}_2(g) ightarrow 2 	ext{MgO}(s). $$When 5.00 g of magnesium burns, the theoretical yield of magnesium oxide is:

Accepted Answer

$$8.29 g$$

Question 4

Strontium phosphate reacts with sulfuric acid to form strontium sulfate and phosphoric acid. What is the coefficient for sulfuric acid when the equation is balanced using the lowest, whole-numbered coefficients?

Accepted Answer

$$2$$

Question 5

Silicon dioxide is heated to melting, it reacts with solid carbon to form liquid silicon and carbon monoxide gas. In an industrial preparation of silicon, $$145.6 kg of$$ $$	ext{SiO}_2$$ reacts with $$65.9 kg of $$carbon. If the percent yield of silicon is $$95.7\%$$, what is the limiting reactant and the theoretical yield (in kg) of silicon?

Accepted Answer

Limiting reactant: SiO$$_2$$; Theoretical yield: $$68.7 kg$$

Question 6

If a reaction mixture initially contains $$24.18 g of$$ $$	ext{KClO}_3$$ and $$17.6 g of$$ $$	ext{CO}_2$$, what mass (in g) of excess reactant is left if the reaction is allowed to go to completion? $$2 	ext{KClO}_3(s) + 3 	ext{CO}_2(g) ightarrow 2 	ext{KCl}(s) + 3 	ext{CO}_2(g) + 3 	ext{O}_2(g)$$

Accepted Answer

$$19.53 g$$ $$	ext{KClO}_3$$

Question 7

Sulfuric acid dissolves aluminum metal according to the reaction: $$2 	ext{Al}(s) + 3 	ext{H}_2	ext{SO}_4(aq) ightarrow 	ext{Al}_2(	ext{SO}_4)_3(aq) + 3 	ext{H}_2(g). $$Suppose you want to dissolve an aluminum block with a mass of $$21.2 g. $$What minimum mass of $$	ext{H}_2	ext{SO}_4 (in g) do $$you need?

Accepted Answer

$$116 g$$

Question 8

Determine the molarity of a solution formed by dissolving $$468 mg of$$ $$	ext{MgI}_2 in $$enough water to yield $$50.0 mL of $$solution.

Accepted Answer

$$0.0936 M$$

Question 9

What volume of $$0.305 M$$ $$	ext{AgNO}_3 is $$required to react exactly with $$155.0 mL of$$ $$0.274 M$$ $$	ext{Na}_2	ext{SO}_4$$ solution? (Hint: You will want to write a balanced reaction.)

Accepted Answer

$$278 mL$$

Question 10

Which of the following is considered a STRONG electrolyte?

Accepted Answer

$$	ext{H}_2	ext{SO}_4$$

Question 11

Which of the following pairs of reactants will result in a precipitation reaction?

Accepted Answer

$$	ext{Na}_2	ext{SO}_4(aq) + 	ext{Ba(NO}_3)_2(aq)$$

Question 12

The titration of $$50.0 mL of an $$unknown concentration $$	ext{H}_3	ext{PO}_4$$ solution requires $$126 mL of$$ $$0.218 M$$ $$	ext{KOH}$$ solution. What is the concentration of the $$	ext{H}_3	ext{PO}_4$$ solution (in M)?

Accepted Answer

$$0.114 M$$

Question 13

Lead(II) ions can be precipitated from aqueous solutions by the addition of aqueous iodide: $$	ext{Pb}^{2+}(aq) + 2 	ext{I}^-(aq) ightarrow 	ext{PbI}_2(s). $$Lead iodide is virtually insoluble in water so that the reaction appears to go to completion. How many milliliters of $$1.500 M$$ $$	ext{HI}$$ must be added to a solution containing $$0.600 g of$$ $$	ext{Pb(NO}_3)_2 to $$completely precipitate the lead?

Accepted Answer

$$8.00 mL$$

Question 14

A sample of an unknown compound occupies $$245 mL at$$ $$298 K $$and $$1.26$$ atm. What is the molar mass of the unknown compound?

Accepted Answer

$$131 g/$$mol

Question 15

A sample of $$	ext{N}_2$$ effuses in $$16.0 s. $$How long will the same size sample of $$	ext{Cl}_2$$ take to effuse?

Accepted Answer

$$21.5 s$$

Question 16

Zinc reacts with aqueous sulfuric acid to form hydrogen gas: $$	ext{Zn}(s) + 	ext{H}_2	ext{SO}_4(aq) ightarrow 	ext{ZnSO}_4(aq) + 	ext{H}_2(g). In an $$experiment, $$225 mL of $$wet $$	ext{H}_2 is $$collected over water at $$27^{\circ}C $$and a barometric pressure of $$785$$ torr. The vapor pressure of water at $$27^{\circ}C is$$ $$26.74$$ torr. The partial pressure of hydrogen in this experiment is ____ atm.

Accepted Answer

$$0.993$$ atm

Question 17

A balloon contains $$0.76$$ mol $$	ext{H}_2$$, $$0.18$$ mol Ne, $$0.011$$ mol Rn and $$0.026$$ mol Cl$$_2 at$$ $$739 mm Hg. $$What is the partial pressure of Ne?

Accepted Answer

$$130 mm Hg$$

Question 18

Calculate the root mean square velocity of argon atoms at $$25^{\circ}C$$. ($$M = 39.95 g/$$mol)

Accepted Answer

$$515 m/s$$

Question 19

Using the graph below, determine the gas that has the highest density at STP.

Accepted Answer

Curve D

General Chemistry 161 – Practice Exam 2 Study Notes

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