Question

A 2.50 g sugar cube (sucrose: C12H22O11) is dissolved in a 350 mL teapot containing 80∘ C water (density of water at 80∘ C= 0.975 g/mL).
What is the molality of the sugar solution?
Express the molality with the appropriate units.

Answer 1

Answer on Question #56064 – Chemistry - General chemistry

Question:

A 2.50 g sugar cube (sucrose: $C_{12}H_{22}O_{11}$) is dissolved in a 350 mL teapot containing $80^{\circ}\mathrm{C}$ water (density of water at $80^{\circ}\mathrm{C} = 0.975\ \mathrm{g/mL}$).

What is the molality of the sugar solution?

Express the molality with the appropriate units.

Answer:

$$C_M = \frac{v}{m} \quad v = \frac{m}{M}$$ $$\rho = \frac{m}{V} \quad m = \rho V$$ $$m(H_2O) = 0.975 \cdot 350 = 341\ \mathrm{g}$$ $$M(C_{12}H_{22}O_{11}) = 343.77\ \mathrm{g/mol}$$ $$v(C_{12}H_{22}O_{11}) = \frac{2.50}{343.77} = 0.01\ \mathrm{mol}$$ $$C_M(C_{12}H_{22}O_{11}) = \frac{0.01}{0.341} = 0.03\ \mathrm{mol/kg}$$

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