Module Four - Energy and Stoichiometry

Question 1

What is combustion?

Answer 1

A reaction in which an element or compound burns in air or oxygen…oxygen is ALWAYS one of the reactants!

Question 2

Combustion of compounds containing carbon and hydrogen always produce what two products?

Answer 2

Water and carbon dioxide. This is also true of compounds that contain hydrogen, carbon, and oxygen.

Question 3

How do we go from grams of reactants to grams of products?

Answer 3

We do mass of reactants –>mols of reactants —> mass of products —> grams of products.

Question 4

How do we find the limiting reagent from mols?

Answer 4

(mols we have of reactant) (theoretical mols of product / theoretical mols of the reactant) = mols that can be produced.

Question 5

How do you convert grams to mols?

Answer 5

grams of substance / molar mass of substance.

Question 6

How do you convert mols to grams?

Answer 6

mols of substance we have * (grams of substance’s molar mass) / (1 mol of substance).

Question 7

How do we determine how many mols of a substance are consumed by mols of another substance?

Answer 7

mols of substance we have * (ratio of the substaces)

ex. 0.02 mols Mg * (2 HCl/1 Mg)

Question 8

How do we determine the theoretical yield?

Answer 8

mols we have of substance * (ratio of mols of reactants, with the substance we have on the bottom) * molar mass = theoretical yield.

ex. 0.0200’mol HCl ‘(1’H2/2’HCl)’‘2.02’g’H2/mol
=’0.0202’g’H2 (called’the’theoretical’yield)