What is the freezing point of a 0.28 m solution of glucose, C6H12O6, in water? (

Question

What is the freezing point of a 0.28 m solution of glucose, C6H12O6, in water? (Kf for water is 1.858°C/m.)

A) 0.26°C B) –0.52°C C) –1.04°C D) –0.26°C E) 0.52°C

For the reaction
IO3–(aq) + 5I–(aq) + 6H+(aq) 3I2(aq) + 3H2O(l)
the rate of disappearance of IO3–(aq) at a particular time and concentration is 2.5 × 10-3 mol/(L · s). What is the rate of appearance of I2(aq)?

A) 1.2 × 10-3 mol/(L · s) D) –7.5 × 10-3 mol/(L · s)

B) 7.5 × 10-3 mol/(L · s) E) 2.5 × 10-3 mol/(L · s)

C) 8.3 × 10-3 mol/(L · s)

If 500 mL of 1.2x10–6 M AgNO3 is mixed with 500 mL of 1.2x10–6 M NaBr, what will occur? For AgBr, Ksp = 5x10–13.

A) 6.0x10–7 mol of AgBr will form.

B) Sodium bromide will precipitate.

C) The concentration of Ag+ will be 1.2x10–6 M.

D) No precipitation will occur.

E) Silver(I) bromide will precipitate.

A solution has a hydroxide-ion concentration of 6.03 × 10–5 M. What is its hydronium-ion concentration?

A) 1.00×10-14 M D) 6.03×10–5 M

B) 1.00×10–7 M E) 6.03×10–19 M

C) 1.66 × 10–10 M

When a 20.5-g sample of an unknown compound is dissolved in 500. g of benzene, the freezing point of the resulting solution is 3.77°C. The freezing point of pure benzene is 5.48°C, and Kf for benzene is 5.12°C/m. Calculate the molar mass of the unknown compound.
A) 105 g/mol B) 61.4 g/mol C) 246 g/mol D) 123. g/mol E) 12.0 g/mol

A solution consisting of 0.218 mol of methylbenzene, C6H5CH3, in 243 g of nitrobenzene, C6H5NO2, freezes at –0.3°C. Pure nitrobenzene freezes at 6.0°C. What is the freezing-point depression constant of nitrobenzene?
A) 7.0°C/m B) 29°C/m C) 1.3°C/m D) 14.0°C/m E) 3.5°C/m

What is the hydroxide-ion concentration of a saturated solution of Ni(OH)2? = 2.0x10–15.

A) 1.6x10–5 M D) 7.9x10–6 M

B) 1.0x10–7 M E) 4.5x10–8 M

C) 1.1x10–4 M

The Ka for hydrofluoric acid is 6.8x104. What is Kb for the fluoride ion?

A) 1.5x10–5 B) 1.5x10–19 C) 6.8 104 D) 6.8x10–10 E) 6.8x1018

What is the pH of a solution that is 0.12 M in acetic acid, HC2H3O2, and 0.70 M in sodium acetate, NaC2H3O2, at 25°C? Ka of acetic acid is 1.8x10-5.
A) 5.51 B) 3.98 C) 1.5 D) 4.74 E) 2.71

At a given temperature, a first-order reaction has a rate constant of 2.0 × 10-3 s-1. How long will it take for the reaction to be 19% complete?

A) 2200s B) 830s C) 1500s D) 46s E) 110s

Explanation / Answer

1.

What is the freezing point of a 0.28 m solution of glucose, C6H12O6, in water? (Kf for water is 1.858°C/m.)

A) 0.26°C B) –0.52°C C) –1.04°C D) –0.26°C E) 0.52°C

dTf = -Kf*m

dTf = -0.28*1.86 = -0.5208 °C

0 - 0.5208 = -0.5208 °c

dTF = -0.5208°C

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