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Old Dec 7th 2017, 02:04 PM   #1
Chem86579
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Please check the tasks

Please check the tasks
1. Calculate the volume of ethanol (with a density of 0.8 g / ml and a mass fraction of 80%) and the volume of water needed to prepare 1000 ml of 0,2-molar C2H5OH).
2. Calculate the mass of sodium chloride and the volume of water needed to prepare 200 g of 1-molar solution of NaCl (density is 1.15 g / ml).
3. Calculate the mass of hydrochloric acid and the volume of water needed to prepare 300 ml of 0.1-molar solution (density of the solution is 1.28 g / ml).

1. m (C2H5OH) = c (C2H5OH) * M (C2H5OH) * V (solution) = 9,2 g
V (C2H5OH) = m (C2H5OH) / (p (C2H5OH) * ω (C2H5OH)) = 14 ml
V (H2O) = V (solution) -V (C2H5OH) = 986 ml
Answer: 14 ml; 986 ml.

2. V (solution) = m (solution) / p (solution) = 0.174 L
m (NaCl) = c (NaCl) * M (NaCl) * V (solution) = 10,179 g
m (H2O) = m (solution) -m (NaCl) = 189.82 g
V (H2O) = 190 ml
Answer: 10.179 g; 190 ml.

3. m (HCl) = c (HCl) * M (HCl) * V (solution) = 1,095 g
m (solution) = V (solution) * p (solution) = 0.3 * 1280 = 384 g
m (H2O) = m (solution) -m (HCl) = 382.905 g
V (H2O) = 383 ml
Answer: 1.095 g; 383 ml.
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