Question 1

Which atomic spectroscopy technique provides the lowest detection limit for trace metal analysis, according to the detection limit ranges shown in the provided figure?

Accepted Answer

Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

Question 2

Atomic emission spectroscopy is exponentially sensitive to temperature because:

Accepted Answer

The number of excited state atoms increases exponentially with temperature.

Question 3

Which of the following is NOT a practical consideration when performing atomic absorption spectroscopy?

Accepted Answer

Reaction enthalpy

Question 4

Given the equilibrium: $$aA + bB \rightleftharpoons cC + dD$$, which of the following is the correct expression for the equilibrium constant $$K$$?

Accepted Answer

$$K = \frac{[C]^c [D]^d}{[A]^a [B]^b}$$

Question 5

If the reaction quotient $$Q$$ for a precipitation reaction is less than $$K_{sp}$$, what will happen when more solid is added to the solution?

Accepted Answer

The added solid will dissolve until equilibrium is reached.

Question 6

For the dissolution of $$PbI_2(s$$) ightleftharpoons $$Pb^{2+}(aq) + 2I^-(aq$$)$$ with K$$_{sp} = 7.9 	imes $$10^{-9}$$, what is the molar solubility of $$PbI_2 in $$pure water?

Accepted Answer

$$1.25 	imes 10$$^{-3}$$ M

Question 7

What is the effect of adding $$Pb^{2+}$$ ions to a saturated solution of $$PbI_2$$?

Accepted Answer

The solubility of $$PbI_2$$ decreases due to the common ion effect.

Question 8

Which of the following is the correct charge balance equation for a solution containing $$H^+$$, $$OH^-$$, $$ClO_4$$^-$$, Mg$$^{2+}$$, CN$$^-$$, Fe$$^{3+}$$, Cl$$^-$$, Fe(CN$$)_$$6^{3-}$$, and $$HCN$$?

Accepted Answer

$$[H^+] + 2[Mg$$^{2+}$$] + 3[Fe$$^{3+}$$] = [OH^-] + [$$ClO_4$$^-] + [CN^-] + [Cl^-] + 3[Fe(CN)_6$$^{3-}$$]$$

Question 9

Which of the following best describes a buffer solution?

Accepted Answer

A solution that resists changes in pH when small amounts of strong acid or base are added.

Question 10

Given a buffer solution containing 0.050 M $$NH_3$$ and 0.050 M $$NH_4Cl$$ with $$pK_a(NH_4$^+) = 9.245$$, and using the activity coefficient $$\gamma(NH_4$^+) = 0.80$$, what is the pH of the buffer?

Accepted Answer

9.34

Question 11

Which of the following statements about the relationship between $$K_a$$, $$K_b$$, and $$K_w is $$correct for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 12

What is the correct expression for the ionic strength $$\mu of a $$solution containing 0.010 M $$Na_2SO_4$$?

Accepted Answer

$$\mu = 0.030 M$$

Question 13

Which ion below has the largest hydrated radius ($$\alpha$$ value)?

Accepted Answer

$$H^+$$

Question 14

Taking into account ionic strength effects, what is the pH of a 0.010 M HBr solution if $$\gamma_{H^+} = 0.914$$?

Accepted Answer

2.04

Question 15

Which of the following best describes the effect of adding $$KNO_3 to a $$solution containing $$Fe(SCN)^{2+} at $$equilibrium?

Accepted Answer

It increases the activity coefficients, shifting the equilibrium position.

Question 16

Which of the following is the correct Henderson-Hasselbalch equation for a buffer using activities?

Accepted Answer

$$pH = pK_a + \log \frac{\gamma_{A^-}[A^-]}{\gamma_{HA}[HA]}$$

Question 17

For a diprotic acid $$H_2A$$, which equation correctly relates $$K_{a1}$$, $$K_{b2}$$, and $$K_w$$?

Accepted Answer

$$K_{a1} 	imes K_{b2} = K_w$$

Question 18

Which of the following is true about the equilibrium constant $$K$$ for a reaction involving solids and liquids?

Accepted Answer

The activities of solids and liquids are set to 1 in the expression for $$K.$$

Chemical Equilibrium, Solubility, and Acid-Base Chemistry: Analytical Chemistry Study Notes

Guida di studio - Domande di pratica

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