Name: _Key____________________
Chapter 7: Section 2 – Mole Ratios
PowerPoint Guided Notes
Holt, Rinehart and Winston, (2008). Physical Science: with Earth and Space Science. Austin,
TX: Holt McDougal
Mole Ratios and YOU!
Balanced Equations and Mole Ratios
A balanced equation tells you the _mole ratios____, or proportion of reactants and products,
in a chemical reaction.
By looking at the ____coefficients of a balanced equation_______, mole ratios can be found.
Law of Definite Proportions
A compound always contains the same __elements__ in the same __proportions__ regardless
of how the compound is made of how much of the compound is formed.
Mole Ratios…
Mole ratios tell you the relative amounts of ______products and reactants_____.
LOOK at the _____coefficients____!
2H2O → 2H2 + O2
_2_ water for every __2_ hydrogen and __1_ oxygen
Mole ratios can be converted to __masses__.
Simply multiply by the _____molecular mass_____ of each substance by the
_____mole ratio________ from the balanced equation.
For example…
O2
→
2MgO
2
1
→
2
24.3
32.0
→
Mass Calculation
24.3g/mol x
2mol
32.0g/mol x
1mol
→
(24.3+16)
40.3
40.3g/mol x
2mol
Mass
(g)
48.6
32.0
→
Equation:
Amount
(mol)
Molar Mass
(g/mol)
2Mg
+
Remember Law of Conservation of Mass to Check Work! 48.6g + 32.0g = 80.6g
80.6