Please complete the questions listed in the LabProbsToDo document that are in the Stoichiometry document. Don’t forget to show your work and to pay attention to units and sig figs. There is a prelab lecture video that does many of these problems for you and introduces you to the way to solve each problem. In addition, I have included directions below. Lab class will be a work time. I can help anyone with questions and/or check the answers that you got. If you would like, we can move into breakout rooms to work on these.
Stoichiometry.pdf
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StoichiometryLabProbsToDo.pdf
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You are required to do the problems listed below, but may also do additional problems in this worksheet for practice. I will post a key for all the problems on the worksheet after the due date so that you can check your work. If you do extra problems, don’t spend too much time on page A32 – the later problems are more important!
Page A32 (problems 1a, f, and j): Determine the molar mass of these compounds (1a is done in prelab lecture). Make sure you multiply the number of each element on the formula by the molar mass of each element and then add them all together. Make sure all the molar masses of your elements have at least 4 significant figures. Remember your multiplication and addition rules for sig figs! Note: Many of these molar masses will be used in later problems. No need to calculate it twice!
Page A33 (Problems 1a, d, and e – 1 a is done in prelab lecture): Convert from mols to grams using molar mass (some calculated in page 32 problems).
Page A34 (Problems 2a, b, 3a, c – 2a and 3a are done in prelab lecture): Convert from grams to moles (also using molar mass). Some molar masses were calculated previously.
Page A35 (problems 2 and 3a – both started in prelab lecture): To find the number of moles of an element in a molecule from the number of moles of molecules, multiply the mols of the molecule by the number of atoms of each element in the formula.
Page A36 (problem 2 – don’t forget to also solve for O2 and 3 – don’t forget to solve for N2 also. Please add converting to grams of O2 for problem 2 and grams of N2 for problem 3): First balance the balanced chemical equations. Then multiply the moles of the given reactant or product in the chemical equation by the mole ratio of the required species to the given species (the mole ratio is determined from the coefficients in the balanced chemical equation. For example:
4A + 2B –> 3C + D
To convert from moles of B to moles of C, multiple moles of B given by (3 moles C/2 moles B)
To convert from moles of B to grams (mass) of C, first solve for mols of C as above, then calculate grams of C using molar mass of C as on page A33.
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