If I want to make a solution that has a 5% concentration of salt, is it correct for me to have 380mL water and 20g salt?
My method behind this was that I wanted a 400g solution, and so since 1mL water is equal to 1g water, I did:
400x0.95=380g water or 380mL water
and
400x0.05=20g salt
Is this correct? If not, why and what would be the correct way to find this?
I found this on the internet, is it correct?
"The easy way to remember how to do % problems is to always remember that % means parts per HUNDRED. So, a 25% salt solution (if it is weight/volume) means 25 grams per 100 mls. Then, if you want only 50 mls, you would use 12.5 grams in 50 mls. If you want only 10 mls of solution, you would use 2.5 grams in the 10 mls. And so forth."
I need to do experimenting for a lab and I only have the scale for the rest of today so I really need an answer so I can start the experiment! It's a simple yes or no!
To determine the correct way to find the concentration of a solution, we need to understand the concept of concentration and how it is calculated. The concentration of a solution is the amount of solute (in this case, salt) dissolved in a given amount of solvent (in this case, water), expressed as a ratio or a percentage.
In your calculations, you correctly determined that you want a 400g solution, which includes both the salt and water. However, water does not always have a 1:1 ratio to volume in milliliters. The density of water is 1g/mL at room temperature, but this can change with temperature and impurities. It is important to know that the density of water may not always be exactly 1g/mL.
To correctly calculate the concentration of the solution, we need to use the mass of the solute and the volume of the solvent. Here's the correct way to find the concentration:
1. Calculate the volume of water needed (in mL) by subtracting the mass of the salt from the desired total mass of the solution:
Volume of water = Total mass of solution - Mass of salt = 400g - 20g = 380g
2. Convert the volume of water from grams to milliliters, assuming the density of water is approximately 1g/mL:
Volume of water = 380mL
3. Calculate the concentration of the salt solution using the formula:
Concentration = (Mass of solute / Volume of solvent) * 100
For your case:
Concentration = (20g / 380mL) * 100 ≈ 5.26%
Therefore, the correct calculation would yield a concentration of approximately 5.26%, not 5%. It's essential to consider the density of water when converting the mass of the solute to the volume of the solvent.