# Solutions in School Chemistry

This is a series of lectures in videos covering Chemistry topics commonly taught in schools.

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Chemistry Lessons

There are several ways to calculate concentration in chemistry, depending on the type of concentration you’re dealing with and the information you have available. Here are the most common methods:

1. Mass Concentration:
Concentration units: grams per liter (g/L), milligrams per liter (mg/L), parts per million (ppm), etc.
Formula: Concentration = Mass of solute / Volume of solution
Example: You dissolve 5 grams of salt in 100 milliliters of water. What is the concentration of the salt solution?
Concentration = 5 g / 0.1 L = 50 g/L

2. Molar Concentration (Molarity):
Concentration units: moles per liter (mol/L)
Formula: Molarity = Moles of solute / Volume of solution (in liters)
Example: You dissolve 10 grams of sodium hydroxide (NaOH) in water to make 250 milliliters of solution. What is the molarity of the solution?
First, calculate the moles of NaOH: 10 g / 40 g/mol = 0.25 mol
Then, calculate the molarity: 0.25 mol / 0.25 L = 1.0 mol/L

3. Percent Concentration (Mass/Volume):
Concentration units: percent weight per volume (% w/v)
Formula: % w/v = (Mass of solute / Volume of solution) x 100%
Example: You mix 20 grams of sugar with 100 milliliters of water. What is the percent concentration of sugar in the solution? % w/v = (20 g / 0.1 L) x 100% = 20%

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