 So I'm going to go through some examples of molarity and calculating molarity and calculating the grams of a substance needed to have a certain molarity solution. So first I'm just going to do a 0.5 molar sulfuric acid. So if we have sulfuric acid, we go to our periodic table and we know hydrogen 1.01 and sulfur 32.07 oxygen. Let's go with 16.00. I'm just rounding these, not changing them really. So we have two atoms of hydrogen per molecule of sulfuric acid. So we have to multiply this by two. We only have one of sulfur, so 32.07. And we have four of oxygen. So I'm going to multiply just to make sure 64. And then I'm going to add those together to give me a mass of 98.09 and that's grams per mol. So 98.09 grams per mol and I want 0.5 moles per liter. The moles cancel. So I'm going to multiply 98.09 times 0.5 and I get 49.05 grams per liter. So I'd have to measure out 49.05 grams and add that to one liter to get a 0.5 molar solution. So I'm going to calculate a six molar sodium hydroxide solution. Sodium we know is 22.99. Oxygen we know is 16. Hydrogen we know is 1.1. So 22.99, 16, 1.01. There's only one of each. Add those up. And we get 40. So six molar, you have 40 and again that's grams per mol. You want six moles per liter. The moles cancel. I'm holding the pen too close here. It gives you 240 grams of sodium hydroxide per liter of solution to get a six molar sodium hydroxide solution. The last example we're going to do is to calculate the number of grams needed to make a 0.25 molar sucrose solution. And sucrose is a bit of a bigger molecule, C12H22O11. And so we do it the exact same way that we've done the other molecules. So the size of the molecule doesn't really matter when you're doing these calculations. So don't let it overwhelm you to see a molecule that big. So we're going to find out the atomic mass of carbon. We know the atomic mass of hydrogen is 1.01. And we know the atomic mass of oxygen is 16. So let's just take a look at our periodic table. We see that carbon is 12.01. So we have 12 molecules of carbon. 22 molecules of hydrogen and 11, I'm sorry, not molecules, atoms. 12 atoms of carbon in this one molecule. 12 atoms of hydrogen and 11 atoms of oxygen. So we're going to have 12.01 times 12, giving us 144.12. We're going to have 1.01 times 22, giving us 22.22. And then 16.00 times 11, giving us 176. So if we add those up, we're going to have 342.34 grams per mole. We set up that same type of equation where we see 342.34 grams per mole. And we know we want 0.25 moles per liter. The moles cancel out 0.25. And that gives us 85.59 grams per liter. So you would need 85.59 grams of sucrose in 1 liter of solution to have a 0.25 molar sucrose solution. So I hope these examples help you understand how you'll calculate molarity in the lab.