How much should 5'8 teen with big bones weight?

How many grams of NaCl(molecular weight = 58.5) would you dissolve in water...?

• 1. How many grams of NaCl (molecular weight = 58.5) would you dissolve in water to prepare a 0.5M NaCl solution with a final volume of 500ml (milliliters)? 2. How many grams of NaCl would you dissolve in water for a total volume of 500ml to prepare a 5% solution? 3. Using a stock solution of 1.0M (molar) NaCl, how would you prepare 100ml of 10mM (milli-molar) NaCl? Could you show the steps for each? This is on a review for my test next week and I do not understand it..

• Answer:

  1. A 1M solution of NaCl would be 58.5 grams in a liter of solution - by definition. So 0.5M would be 29.25 grams in a liter of solution - cutting the NaCl in half. Then 14.625 grams of NaCl in 500 ml (0.5 liter) will also be 0.5M - cutting in half both the NaCl and the final volume. 2. A 5% solution in 100 ml would require 5 gm of NaCl - 5 gm is 5% of 100 gm (=100 ml). So 500 ml of a 5% solution would require 25 gm of NaCl - 5 gm x 5 = 25 gm. 3. 10mM = 0.01M. So starting with a 1.0M solution, dilute it 100 times - 1.0 divided by 100 = 0.01M (by moving the decimal point 2 places to the left, 1.0 --> 0.01) To dilute the 1.0M stock solution 100 times, and end up with 100 ml, requires 1 ml of stock and 99 ml of H2O