1. Section 3.6: Quantitative Information from Balanced Equations

2. 3.6: Quantitative Information from Balanced Equations.
The coefficients in a balanced equation represent both the relative numbers of molecules involved in the reaction, AND THE RELATIVE NUMBERS OF MOLES, and therefore the relative masses:
2 H2(g) + O2(g) → 2 H2O (l)
2 molecules + 1molecule 2 molecules
2 moles mole moles
= 2 x (2.0) g g → 2 x (18.0) g

3. Weights of products and reactants in a balanced equation:
We can thus work out how many grams of water will be produced by burning given amounts of H2 and O2 together.
Example: The combustion of butane:
2 C4H10(l) O2(g) → 8 CO2(g) + 10 H2O(l)
2 moles 13 moles 8 moles moles
2 x 58.0 g x 44.0 g
M. Wt. C4H M. Wt. CO2

4. Conversion Sequence Grams Reactant Moles Reactant Moles Product
Grams Product

5. How many grams of CO2 will be obtained by burning 1.00 g of C4H10?
2C4H O2  8CO2(g) + 10H2O(g)
1) Grams reactant → Moles reactant
1.00 g x 1mol C4H10 = mol C4H10
58 g C4H10
2) Moles reactant → Moles product
mol C4H10 x 8mol CO2 = moles CO2
2 mol C4H10
3) Moles product → Grams product
mol x 44.0 g CO2 = g CO2
1 mol CO2

6. Homework
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