EIT Chemistry 1

Question 1

What is the molarity of a solution prepared by dissolving 40 g of NaOH (MW = 40 g/mol) in 1 liter of water?

Accepted Answer

1.0 M

Answer

Molarity = moles/volume = (40 g ÷ 40 g/mol) / 1 L = 1.0 M.

Question 2

What is the pH of a 0.01 M HCl solution?

Accepted Answer

2

Answer

pH = −log[H⁺] = −log(0.01) = 2.

Question 3

Which of the following is an example of an exothermic reaction?

Accepted Answer

Combustion of methane

Answer

Combustion of methane releases heat to the surroundings, making it exothermic.

Question 4

The ideal gas law is PV = nRT. What are the SI units of the universal gas constant R?

Accepted Answer

J/(mol·K)

Answer

R = 8.314 J/(mol·K) in SI units, relating energy to amount of substance and temperature.

Question 5

For a first-order reaction with rate constant k = 0.693 min⁻¹, what is the half-life?

Accepted Answer

1.0 min

Answer

t½ = ln(2)/k = 0.693/0.693 = 1.0 min for a first-order reaction.

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