Question

How many grams of CaCl2 are needed to make a solution with a concentration of 3.0 m from 2.25 kg of water?

A. 7.5 x 102 g CaCl2
B. 7.50 kg CaCl2
C. 7.50 × 10–2 kg CaCl2
D. All of the Above
E. None of the Above

Answer 1

Answer on Question #75168, Chemistry / General Chemistry

How many grams of $\mathrm{CaCl}_2$ are needed to make a solution with a concentration of $3.0\,\mathrm{M}$ from $2.25\,\mathrm{kg}$ of water?

A. $7.5 \times 10^{2} \, \mathrm{g} \, \mathrm{CaCl}_2$

B. $7.50\,\mathrm{kg} \, \mathrm{CaCl}_2$

C. $7.50 \times 10^{-2} \, \mathrm{kg} \, \mathrm{CaCl}_2$

D. All of the Above

E. None of the Above

Solution

$$C_m = \frac{v}{v}; \, v = C_m V$$ $$v(\mathrm{CaCl}_2) = 3 \times 2.25 = 6.75\,\mathrm{(mole)};$$ $$m(\mathrm{CaCl}_2) = v(\mathrm{CaCl}_2) \times M(\mathrm{CaCl}_2) = 6.75 \times 111 = 749.25\,\mathrm{(g)}$$

Answer

A. $7.5 \times 10^{2} \, \mathrm{g} \, \mathrm{CaCl}_2$

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