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April 30, 2016

# Homework Help: Chemistry

Posted by Leora on Friday, March 25, 2011 at 11:03am.

1. What is the percent by mass of a solution that contains 50 grams of solute dissolved in 200 grams of solution? What is the concentration of the same solution in parts per million?

2. What is the percent mass of a solution that contains 75 grams of salt dissolved in 150 grams of water? What is the concentration of the same solutionin parts per million?

3. If a solution is 25% NaCl by mass, what is the mass of salt contained in 150 grams of the solution?

4. What mass of solute is needed to prepare 500 grams of a 15% by mass solution?

5. What mass of sugar is present in 2.50 kilograms of solution that is 30% by mass?

6. What is the mass of solute present in 250 grams of a solution that is 12% by mass?

7. The average salinity off sea water is 34.7%. What is this quantity expressed in parts per million?
• Chemistry - DrBob222, Friday, March 25, 2011 at 10:53pm

1. What is the percent by mass of a solution that contains 50 grams of solute dissolved in 200 grams of solution? What is the concentration of the same solution in parts per million?

% w/w = (g solute/g soln)*100 = 25% w/w\.

25g/100 = ??ppm.
What must you multiply 100 by to get 1,000,000? That would be 10^4. So multiply 25 by 10^4 and you will have 2.5^10^4/10^6 = 250,000 ppm