Q: When 20.0 mL of 0.035 M $$\mathrm{$$ZnI_2$$} is $$mixed with 15.0 mL of 0.045 M $$\mathrm{$$AgNO_3$$}$$, will a precipitate of $$\mathrm{AgI}$$ form? ($$K_{sp}$$ for $$\mathrm{AgI} is$$ $$8.3 \times 10$$^{-17}$$)

$$Q_{sp} = 4.3 \times 10$$^{-6}$$ and a precipitate will form

Question 1

Which of the following salts will produce a solution with a pH of 7.00 when dissolved in water?

Accepted Answer

KClO4 only

Question 2

In the titration of a NaOH solution with HCl, which statement best describes the titration curve?

Accepted Answer

The initial pH is high and the equivalence point pH is equal to 7.

Question 3

Calculate the pH after adding 25.0 mL of 0.125 M NaOH to 50.0 mL of 0.100 M HCl.

Accepted Answer

1.60

Question 4

A solution is prepared by titrating 15.0 mL of 0.274 M acetic acid ($$\mathrm{HC_2H_3O_2}) $$with 28.0 mL of 0.125 M NaOH. $$K_a$$ for acetic acid is $$1.8 	imes 10$$^{-5}$$. What is the pH after the addition?

Accepted Answer

5.50

Question 5

Write the $$K_{sp}$$ expression for $$\mathrm{Zn_3$(PO_4$)_2}.$$

Accepted Answer

$$K_{sp} = [Zn$$^{2+}$$]^3[PO_4$^{3-}]^2$$

Question 6

Which of the following salts would be classified as similarly 'insoluble' salts?

Accepted Answer

FeS and Zn3P2

Question 7

The molar solubility of $$\mathrm{$$CaCO_3$$} is$$ $$1.3 	imes 10$$^{-4}$$ M. What mass of $$\mathrm{$$CaCO_3$$}$$ will dissolve in 100 mL of water?

Accepted Answer

$$2.0 	imes 10$$^{-3}$$ grams

Question 8

Calculate the solubility of $$\mathrm{$$PbCl_2$$} in a$$ $$0.100 M $$HCl solution. ($$K_{sp}$$ for $$\mathrm{$$PbCl_2$$} is$$ $$1.8 	imes 10$$^{-5}$$)

Accepted Answer

$$1.8 	imes 10$$^{-3}$$ M

Question 9

When 20.0 mL of 0.035 M $$\mathrm{$$ZnI_2$$} is $$mixed with 15.0 mL of 0.045 M $$\mathrm{$$AgNO_3$$}$$, will a precipitate of $$\mathrm{AgI}$$ form? ($$K_{sp}$$ for $$\mathrm{AgI} is$$ $$8.3 	imes 10$$^{-17}$$)

Accepted Answer

$$Q_{sp} = 4.3 	imes 10$$^{-6}$$ and a precipitate will form

Question 10

In a selective precipitation, $$\mathrm{Ca$$^{2+}$$}$$ and $$\mathrm{Sr$$^{2+}$$}$$ are being precipitated by the addition of $$\mathrm{Na_2CO_3}. $$Calculate the $$[\mathrm{Sr$$^{2+}$$}]$$ still in solution when $$\mathrm{$$CaCO_3$$}$$ begins to precipitate. ($$K_{sp}$$ for $$\mathrm{$$CaCO_3$$} is$$ $$1.1 	imes 10$$^{-8}$$, K$$_{sp}$$ for $$\mathrm{$$SrCO_3$$}$$ is 1.6$$ 	imes $$10^{-9}$$, both initial concentrations $$2.0 	imes 10$$^{-3}$$ M)

Accepted Answer

$$5.5 	imes 10$$^{-6}$$ M

Question 11

In the Qualitative Analysis Lab, $$\mathrm{CuS}$$ and $$\mathrm{Bi_2S_3}$$ were separated from $$\mathrm{ZnS}$$ and $$\mathrm{FeS} by $$controlling the concentration of which ion?

Accepted Answer

$$\mathrm{S$$^{2-}$$}$$

Question 12

Write the $$K_f$$ expression for $$\mathrm{Al(OH)_4^-}.$$

Accepted Answer

$$K_f = \frac{[Al(OH)_4^-]}{[Al$$^{3+}$$][OH^-]^4}$$

Question 13

Calculate the $$[\mathrm{Au^+}] in a$$ $$0.500 M$$ $$[\mathrm{Au(CN)_2}]^-$$ solution. ($$K_f$$ for $$[\mathrm{Au(CN)_2}]^- is$$ $$2.3 	imes 10$$^{45}$$)

Accepted Answer

$$4.7 	imes 10$$^{-24}$$ M

Question 14

In the Qualitative Analysis Lab, $$\mathrm{Zn$$^{2+}$$}$$ ions were separated from $$\mathrm{Fe$$^{3+}$$}$$ ions by the addition of which ion?

Accepted Answer

$$\mathrm{OH^-}$$

Question 15

A patient is treated for lead poisoning using a chelating agent that forms a highly stable complex with $$\mathrm{Pb$$^{2+}$$}. $$Which equilibrium constant is most relevant to the effectiveness of this treatment?

Accepted Answer

$$K_f of $$the $$\mathrm{Pb}-$$chelate complex

Question 16

Which of the following best explains why $$\mathrm{$$NaNO_2$$}$$ produces a basic solution when dissolved in water?

Accepted Answer

The $$\mathrm{NO_2$^-}$$ ion hydrolyzes to produce $$\mathrm{OH^-}.$$

Question 17

A solution contains $$\mathrm{Fe$$^{3+}$$}$$ and $$\mathrm{Zn$$^{2+}$$}. $$Which reagent would you add to selectively precipitate only $$\mathrm{Fe(OH)_3}$$?

Accepted Answer

Add $$\mathrm{OH^-}$$ until $$[OH^-]$$ just exceeds the $$K_{sp}$$ for $$\mathrm{Fe(OH)_3}.$$

Chemistry 1120 – Test 3 Study Guidance

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