March 7, 2011

--Molarity and Stoichiometry Relations--

-Using our knowledge of mole conversions

-Molarity (M)

-moles

-mass

-volume

-You can use mole to convert from grams, litres, moles, etc.

- example.

Find the number of grams of Cu, from 120mL of 0.300M of CuSo4 react with Zn?

Solution:

-Write a balanced equation

(1)CuSo4 + (1)Zn => (1)ZnSO4 + (1)Cu

-Conversion from M to moles to grams

(0.300M / 0.120L) = 0.036 mol CuSO4

0.036 mol CuSO4 x ( 1 mol Cu / 1 mol CuSO4 ) x ( 63.5g / 1 mol Cu )

= 2.30g Cu

-REMINDER-

-important things to remember

-22.4 L/mole

-M = Mole / L

-Mole = M x L

-L = Mole / M

-Remembering these important information, you can convert using even the smallest amount of information given.

- example 2.

Calcium Carbonate decomposes into Carbon Dioxide and Calcium Oxide. Find the number of grams of CaCO3 for 9.0L of CO2 at STP?

-Solution

Write a balanced equation

(1)CaCO3 => (1)CO2 + (1)CaO

9.0L CO2 x (mol/22.4L) x (1 mol CaCO3/1 mol CO2) x (100.1g/1 mol CaCO3)

=40. g CaCO3

A good video tutorial:

Mar 1 2011 - Stoichiometry

Stoichiometry is a greek word which are stoichio (element) and metry (measurement).

Stoichiometry is study of quantitative relationship between the amount of reactants used in a chemical reaction and the amount of products produced by the reaction.

Here's an example!

* You need to balance the equation before do this.