Lecture 12.2b- Gram-Gram Stoich

1. A sample of NaCl has a mass of 150g. How many moles does the sample contain?

2. What is the mass of 5.3 moles of water?

5.3 mol x mol

181

g

Bellwork- mole gram conversions

150g NaCl x

gmol 1

58.44= 2.57 moles NaCl

= 95.4 grams

STOICHIOMETRY

You must be able to

1.Balance equations

2.Convert between moles and grams

For Stoichiometry–

1.You ALWAYS use moles!! If you are not given moles you must convert to moles.

For Stoichiometry–

1.You ALWAYS use moles!! If you are not given moles you must convert to moles.

2.Use the mole ratio to convert between compounds.

Most stoichiometry problems involve masses.


1.Convert grams to moles using the molar mass of the given compound.



2.Convert moles of the given compound to moles of the wanted compound using a mole ratio.



2.Convert moles of the given compound to moles of the wanted compound using a mole ratio.

3.Convert moles to grams using the molar mass of the new compound.

12.3

Step 1- CONVERT TO MOLES!!

5.4g H2 x ______ = 2.7mol H21 mole2.0g

Step 2- Use a mole ratio to convert to moles of another compound.

2.7mol H2 x mol H2

mol NH3

32

= 1.8 mol NH3

Step 1- CONVERT TO MOLES!!

5.4g H2 x ______ = 2.7mol H21 mole2.0g

Step 2- Use a mole ratio to convert to moles of another compound.

2.7mol H2 x mol H2

mol NH3

32

= 1.8 mol NH3

Step 3- Convert moles to grams

1.8 mol NH3 x 1 mole NH3

17g = 31g NH3

Problem-Solving Approach

Given(G) Wanted(W)

Divide to get moles

Use mole ratio multiply to

get g or L

N2(g) + 3H2(g) 2NH3(g)

2. What volume of H2 is required to react with 3.0 L of N2, and what volume of NH3 is produced at STP?

a. volume of H2 = 9.0 L, volume of NH3 = 6.0 L

b. volume of H2 = 3.0 L, volume of NH3 = 3.0 L

c. volume of H2 = 3.0 L, volume of NH3 = 6.0 L

d. volume of H2 = 1.0 L, volume of NH3 = 1.5 L

3. Automotive airbags inflate when sodium azide, NaN3, rapidly decomposes to its component elements via this reaction:

2NaN3 2Na + 3N2.

How many grams of sodium azide are required to form 5.00 g of nitrogen gas?

a. 11.61 g

b. 17.41 g

c. 7.74 g

d. 1.36 g

Lecture 12.2b- Gram-Gram Stoich

Education

Transcript of Lecture 12.2b- Gram-Gram Stoich