- 63 Views
- Uploaded on
- Presentation posted in: General

Unit G

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Unit G

Mathematics of Chemical Reactions

(Gravimetric Stoichiometry)

- This unit studies the use of mathematics in balanced equations to determine the amount of reactant needed or predict the amount of product that will be formed when the reaction is run.

- Gravimetric: involves the use of a balance
- Gravi-: using gravity (mass)
- -metric: to measure

- Stoichiometry(based on two Greek words)
- Stoicheion: “of the elements”
- -metry: to measure

- Stoichiometry is a review:

- Must understand the formulas of elements and ions (Unit B)
- Must be able to write chemical names and formulas (Unit D)
- Must be able to write and balance chemical equations (Unit E)
- Must be able to convert mass to moles and moles to mass (Unit F).

- Practical Importance of Stoichiometry

- The gasoline-to-air mixture in a car.
- The proper proportions of ingredients in recipes.
- Antacid tablets to neutralize stomach acid may be harmful in excess.

- Reading Balanced Equations in terms of Moles

- Generalized Solving Method

- Write the balanced chemical equation.
- List given amount under appropriate substance. Put a (?) with the necessary units under the substance you are looking for.
- Multiply the given amount by the mole ratio:

- Round final answer using appropriate rules.

Example #1:How many moles of hydrogen are required to react exactly with 4.13 mol of oxygen?

2 H2(g) + O2(g) 2 H2O(g)

? mol 4.13 mol

Example #2:Determine the number of moles of natural gas (methane) that must undergo combustion to produce 1.62 mol of water vapor.

CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g)

? mol 1.62 mol