Download ___Mg + ___O ___MgO • Mole : Mole ratio

Stoichiometry is a process used by chemists to determine accurate chemical quantities of both products and reactants in a chemical reaction.
 Stoichiometry is not possible without properly written and balanced chemical
equations.
 Balanced chemical equations give chemists a simple way of determining the amount of product that
a given amount of reactants will form

___Na
+
___MgCl2
___Mg
+
___NaCl
- If 2 moles of Na and 1 mole of MgCl2 are reacted, ____ moles of NaCl will be produced.
- To produce 1 mole of Mg you would need ____ moles of Na.

Mole : Mole ratio - determined by the coefficients of a balanced chemical equation
- needed to predict the chemical quantities of any reaction
___Mg
+
___O2
___MgO
What is the mole : mole ratio of magnesium (Mg) and oxygen (O2)
What is the mole : mole ratio of magnesium oxide (MgO) and oxygen (O2)
- Stoichiometry is like
cooking. To figure out
the amount of ingredients
you will need use your
Mole Road Map
_____ : _____
_____ : _____
If you need to make 10 grams of CO2 using the following reaction how many grams of
baking soda NaHCO3 will you need.
+
NaHCO3
HCl
NaCl
+
H2O
+
CO2
To answer stoichiometric problems focus on the quantity given and the quantity
you are looking for!
1) Balance the following equation:
C
+
SO2
CS2
a. How many moles of CS2 form when 6.30 moles of C reacts?
b. How many moles of C are needed to react with 7.24 moles of SO2?
+
CO
2) Balance the following equation:
Al
+
CuSO4
Cu
+
Al2(SO4)3
a. How many grams of copper are formed when 25.0 grams of Al reacts with excess CuSO4?
3) Balance the following equation:
CaCO3
CaO
+
CO2
a. How many moles of CO2 are formed when 250 g of CaCO3 decomposes to form CaO and CO2
b. How many grams of CO2 would be produced if 2 moles of CaCO3 decomposed?
4) You need to make 550 grams of Al2O3.
Al
+
O2
Al2O3
a. How many liters of O2 are needed?
b. How many atoms of Al are needed?
To calculate the percent yield, you will need to know:
% Yield = Actual Yield
x 100
Theoretical Yield
Actual Yield = The experiment amount of product that was
produced during the laboratory experiment.
Theoretical Yield = The calculated amount of product
determined by stoichiometry that
would be the maximum that could be
produced.
*Both the actual yield & theoretical yield need to be in
the same unit and be the same chemical in order to
compare them to determine a percent yield.
1) What is the percentage yield if 5.50 grams of hydrogen gas
reacts with nitrogen gas to form 20.4 grams of ammonia
(nitrogen trihydride)?
2) What is the percent yield when 2.37 grams of silver nitrate
reacts with sodium hydroxide to produce water, sodium nitrate
and 1.55 grams of silver oxide?
*Limiting Reactant: the chemical substance that
‘runs’ out first in a chemical reaction. This is the
chemical that determines how much of the
product(s) are made.
*The true amount of excess reactant is also determined by the limiting reactant.
*Excess reactants: chemical substances that you
have more than enough needed for the reaction.
For example, let’s make some tricycles.
We will need the following per tricycle:
1 handle bar (Hb), 1 seat (S), 3 wheels (W), 1 frame (F),
2 pedals (P)
1 Hb + 1 S + 3 W + 1 F + 2 P —> 1 HbSW3FP2
Now, if you had in your possession 30 of each item, answer the following questions.
1) How many tricycles get built?
2) How many handlebars are used?
3) How many seats are used?
4) How many wheels are used?
5) How many frames are used?
6) How many pedals are used?
7) What item is the limiting factor?
Pb(NO3)2 + KI  PbI2 + KNO3
1) Which substance is the limiting factor when 2.96 grams of
lead (II) nitrate reacts with 3.22 grams of potassium iodide?
2) How many grams of the excess reactant will be used during
this experiment?
3) When the reaction is complete, how many grams of lead (II)
iodide will be created?