Question

An average person needs about 10000 kJ energy per day. The amount of glucose (molar mass = 180.0 g mol⁻¹) needed to meet this energy requirement is ______ g. (Nearest integer)

(Use: Δ_CH (glucose) = −2700 kJ mol⁻¹)

Options

• 500 g

• 598 g

• 350 g

• 667 g

Answer 1

An average person needs about 10000 kJ energy per day. The amount of glucose (molar mass = 180.0 g mol⁻¹) needed to meet this energy requirement is 667 g.

Explanation:

Given:

Energy needed per day = 10,000 kJ

Molar mass of glucose = 180 g/mol

Combustion enthalpy of glucose (ΔC H) = –2700 kJ/mol

Step 1: How many moles of glucose are needed?

Moles of glucose = `(10000)/(2700) ≈ 3.7037` mol

Step 2: Convert moles to grams

Mass = moles × molar mass = 3.7037 × 180 ≈ 666.7g