If i change the concentration of the 3% hydrogen peroxide solution to 1.5%, am I changing its concentration or percent concentration?
both. The 3% is 3g/100 mL (w/v) and the 1.5% is only 1.5g/100 mL so you have changed the concentration. Obviously there is less H2O2/100 mL in the 1.5% solution. But you have changed the percent too. Obviously, from 3% to 1.5%.
When you change the concentration of a solution, you are actually changing both its concentration and percent concentration.
Concentration refers to the amount of solute (in this case, hydrogen peroxide) dissolved in a given amount of solvent (usually water). It is typically expressed in terms of mass per unit volume or moles per unit volume.
Percent concentration, on the other hand, represents the proportion of the solute in the solution. It is calculated by dividing the mass or moles of solute by the total mass or moles of the solution and multiplying by 100.
In your case, if you change the concentration of a 3% hydrogen peroxide solution to 1.5%, you are changing both its concentration and percent concentration. The concentration will decrease, as there will be less hydrogen peroxide in the solution. Similarly, the percent concentration will decrease because the proportion of hydrogen peroxide in the solution will be lower.