What is the percent by weight of a solution prepared by dissolving 25 g of NaCl in 150 g of water? What is the volume of water in a 1 L bottle of 37% rubbing alcohol by volume?
%NaCl = (grams NaCl/total mass)*100 = ?
37% alcohol by volume means 37 mL alcohol in 100 mL soln or 37 mL alcohol per (37 mL alcohol + 63 mL H2O). In 1 L that will be 10 x that or 370 mL alcohol in (370 mL alcohol + 670 mL H2O).
To find the percent by weight of a solution, you need to divide the weight of the solute (in this case NaCl) by the weight of the solution (NaCl + water), and then multiply by 100.
For the first question, we have 25 g of NaCl dissolved in 150 g of water. The weight of the solution is the sum of the weights of NaCl and water, which is 25 g + 150 g = 175 g.
Next, we can calculate the percent by weight using the formula:
Percent by weight = (weight of solute / weight of solution) * 100.
So, for this case, the percent by weight is (25 g / 175 g) * 100 = 14.29%.
As for the second question, to find the volume of water in a 1 L bottle of 37% rubbing alcohol by volume, we need to find the volume of alcohol in the solution and subtract it from the total volume.
If the rubbing alcohol is 37% alcohol by volume, it means that 37% of the volume of the solution is alcohol and the remaining 63% is water. So, to find the volume of alcohol, we multiply 37% by 1 L (total volume):
Volume of alcohol = 0.37 * 1 L = 0.37 L.
Since we want to find the volume of water, we can subtract the volume of alcohol from the total volume:
Volume of water = Total volume - Volume of alcohol = 1 L - 0.37 L = 0.63 L.
Therefore, the volume of water in a 1 L bottle of 37% rubbing alcohol by volume is 0.63 L.