104_lab9 - Dr. Littles learning goals for this lab:...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Dr. Little’s learning goals for this lab: Calculate molar masses from formulas Find moles of liquid reactant using density and molar mass Find moles of a solid reagent using molar mass Find theoretical yield of a chemical reaction Determine limiting reactant from calculations (calculate how much product can be made from EACH reactant; the reactant that makes less product limits reaction and is limiting reactant) Calculate % yield % yield = actual yield (measured) x 100% theoretical yield (calculated) Understand why we don’t get 100% yield in most reactions
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
A chemical reaction is a recipe. We need to be able to find out how much product we can make in the same way that we do with a baking recipe: If we have 6 crusts, how many pies can we make? (NOTE: also called theoretical yield) How many apples do we need? (NOTE: the word PER means divide by) With 8 crusts & 15 apples, how many pies can I make? Since 3 pies is less than 4 pies, the apples will run out before the crusts, and only 3 pies can be made. (NOTE: apples are the limiting reagent) apples pie apples pies 15 5 3 1 5 3 = × = × 2 crusts + 5 apples 1 pie pies apples pie apples pies crusts pie crusts 3 5 15 5 1 15 4 2 8 2 1 8 = = × = = × pies crusts pie crusts 3 2 6 2 1 6 = = ×
Background image of page 2
Stoichiometric Ratio The coefficients tell us how many moles of one reactant/product are related to how many moles of another. y and x are the coefficients in front of chemicals Y and X The ratio is called the “stoichiometric ratio” Y moles X moles x Y moles y X moles # # = ×
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Steps for Stoichiometry problems (Dimensional analysis method) Write correct formulas for all reactants and products, and balance the equation Identify the given substance (or substances ** ) and the desired substance Convert qty of given substance into moles (grams ÷ MM = moles) (if needed) Convert moles given into moles desired: (Use the coefficents in the balanced reaction for ? and ??) Convert the moles desired into alternate units (usually grams) if the problem asks (moles x MM = grams) ** if two or more givens, must do ALL STEPS for EACH, then pick smaller answer (limiting reactant) desired moles given moles desired moles given moles # ?? ? # = ×
Background image of page 4
Find moles of solid and liquid reactants Remember we have 3 mole equations: To find the moles of a liquid from the V of liquid, it is tempting to use the moles of solution formula BUT if we have a pure liquid, we need to use the moles of pure formula since there is no solution.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/20/2010 for the course CHEMISTRY 02 taught by Professor Little during the Spring '10 term at S.E. Louisiana.

Page1 / 14

104_lab9 - Dr. Littles learning goals for this lab:...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online