Homework Sourse1 How many mL of a 225 vv ethanol solution would you need to
1. How many mL of a 22.5% (v/v) ethanol solution would you need to measure out in order to have 12.5 mL of ethanol? (Molar mass of ethanol is 46.07 g/mol)
2. How many grams of NaOH are in a 225.0 mL sample of a 2.5 M solution of NaOH? (Molar mass of NaOH is 40.0 g/mol)
3. How many grams of NaCl are in a 388.5 g sample of a 1.25% (m/m) NaCl solution? (Molar mass of NaCl is 58.54 g/mol)
1. How many mL of a 22.5% (v/v) ethanol solution would you need to measure out in order to have 12.5 mL of ethanol? (Molar mass of ethanol is 46.07 g/mol)
2. How many grams of NaOH are in a 225.0 mL sample of a 2.5 M solution of NaOH? (Molar mass of NaOH is 40.0 g/mol)
3. How many grams of NaCl are in a 388.5 g sample of a 1.25% (m/m) NaCl solution? (Molar mass of NaCl is 58.54 g/mol)
1. How many mL of a 22.5% (v/v) ethanol solution would you need to measure out in order to have 12.5 mL of ethanol? (Molar mass of ethanol is 46.07 g/mol)
2. How many grams of NaOH are in a 225.0 mL sample of a 2.5 M solution of NaOH? (Molar mass of NaOH is 40.0 g/mol)
3. How many grams of NaCl are in a 388.5 g sample of a 1.25% (m/m) NaCl solution? (Molar mass of NaCl is 58.54 g/mol)
Solution
1) 100ml sol contains 22.5 ml ethanol ,
to get 12.5 ml ethanol we need = (12.5/22.5) x100 = 55.55 ml solution.
2) mass of NaOH = Molarity x vol x Molar mass = 2.5 x0.225x40 = 22.5 gm ,
3) 388.5g sample conatins 388.5 x(1.25/100) = 4.856 grams NaCl
