1. Math for Chemistry
It CAN be done!!

2. Strategies For multi-step problems, you have 2 choices:
Solve one step at a time (the answer of one step becomes the starting point of the next step)
Use a “T” bar to connect all of the steps
“T” bar

3. Strategies
So far, we have solved steps individually. Let’s look at the “T” bar strategy. For the reaction N2 + 3 H2 2 NH3 To convert grams to grams: How many grams of N2 are needed to produce 46 g NH3?

4. Procedure How many grams of N2 are needed to produce 46 g NH3?
N2 + 3 H NH3
First, convert grams of NH3 to moles of NH3
Next, convert moles of NH3 to moles of N2
Finally, convert moles of N2 to grams of N2

5. Procedure
When using the “T” bar, you would line up each conversion factor on the line: N2 + 3 H2 2 NH3 = g N2

6. Learning Check
If 6 g NaOH react with excess MgCl2, how many grams of Mg(OH)2 will be produced? 2 NaOH + MgCl2 Mg(OH)2 + 2 NaCl What are the steps? Use the stepwise strategy or the “T” bar strategy to solve.

7. Learning Check
100 mL of a 6.0 M solution of HCl is used to react with excess Zn metal as shown below. How many grams of H2 gas is produced? Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g) What are the steps? Use one of the strategies to solve.