Chemistry Questions & Answers - Free Online Practice

3,106.

If 10.8 g of silver is deposited in a silver coulometer volume of oxygen liberated is?

0.56 dm³

5.60 dm³

11.20 dm³

22.40 dm³

View answer & explanation

Correct answer is A

Ag⁺ + e^-
H = 108 g Ag
= 0.11 10.8 Ag
4OH → O₂ + 2H₂O + 4e
4F ↔ 1mole O₂
4F = 22.4 dm³ χ 0.1 = 0.56 dm³

3,107.

What volume of 11.0 M hydrochloric acid must be dilute to obtain 1 dm³ of 0.05 M acid?

0.05 dm³

0.10 dm³

0.55 dm³

11.0 dm³

View answer & explanation

Correct answer is A

No explanation has been provided for this answer.

3,108.

What is the concentration of H⁺ ions in moles per dm³ of a sodium of pH 4.398?

4.0 χ 10^-5

0.4 χ 10^-5

4.0 χ 10^-3

0.4 χ 10^-3

View answer & explanation

Correct answer is A

PH = -log (H⁺)
(H⁺) = 10^-4.348 = 4.0 χ 10^-5

3,109.

2.0g of a monobasic acid was made up to 250 cm³ with distilled water. 25.00 cm³ of this solution required 20.00cm³ of 0.1 M NaOH solution for complete neutralization. The molar mass of the acid is?

200 g

160 g

100 g

50 g

View answer & explanation

Correct answer is C

M_a = (M_bV_b)/(V_a) = (0.1 m χ 20 cm³)/(25cm) = 0.08 m

M = (concentration in g/dm³)/(m) = (8)/(0.08) = 100 g

3,110.

Na₂C₂O₄ + CaCl₂ → CaC₂O₄ + 2NaCl. Given a solution of 1.9g of sodium oxalate in 50g of water at room temperature, calculate the minimum volume of 0.1 M calcium oxalate using the above equation?

1.40 χ 10² dm³

14.0 χ 10² cm³

1.40 χ 10^-2 dm^-2

14.0 χ 10^-2 cm³

View answer & explanation

Correct answer is A

Na₂C₂O₄ + CaCl₂ → CaC₂O₄ + 2NaCl

molar mass of Na₂C₂O₄ = 134

molarity in 1000g H₂O = (1.9)/(134) = 0.014 m

but in 502 g mole = (0.014)/(50) χ 1000 = 0.28 m

M₁V₁ = M₂V₂
V₂ = (M₁V₁)/(M₂) = (0.28 χ 50)/(0.1) = 140
= 1.40 χ 10² dm³