A solution contains 24.8g of sucrose which has a molecular formula of C12H22O11 and it's dissolved in 550 grams of water. Calculate the molality of the solution. So remember, molality equals moles of solute divided by kilograms of solvent. Our solute is the amount that's smaller, so 24.8g of sucrose would be our solute, and then the larger amount will be our solvent. So water here is a solvent.
So what I'm going to do first is the easier one. Let's just convert grams to kilograms. So we have here 550 grams of water and remember 1K is 103 so 1 kilogram is 103 grams, so that's 0.550 kilograms. Next I need to find the moles of sucrose. So we have 248 or 24.8, sorry, 24.8 grams of sucrose. For every one mole of sucrose, how many grams do we have?
So we have 12 carbons, 22 hydrogens, 11 oxygens. Their combined mass comes out to 342.296. So here grams cancel out and we'll have our moles, which comes out to be 0.07245 moles. So I'm going to take those moles and plug them over here. Moles of sucrose. So when I divide my moles by my kilograms, I'll get my molality.
So here 24.8 has three sig figs, 550.0 has four sig figs. Always go with the least number of sig figs. So we're going to have three sig figs at the end. So this comes out to be 0.132 molal. So this would be our final answer.