Chapter WOC 9

Mole TO Mole

Problems1. Write the equation that describes the reaction.2. Balance the equation.3. The coefficients are mole-to-mole ratios. Determine what is

given and what is needed.4. Put the given and needed moles in boxes and draw the “mole

bridge” between the boxes.5. Mark the bridge with the coefficients.6. Divide then multiply to find the unknown number of moles.

Rodents of Unusual Size

Now that you have mastered mole to mole problems, let’s

try something more complicated.

You can use your mole skills to solve many types of

problems!

•Mole to Mole •Mole to Mass•Mass to Mass•Mass to Volume•Volume to Volume•Volume to MoleBlah blah blah!

No matter which type of problem you need to solve, the four box method will help organize information.

Known Unknown

Moles known

÷ divide

÷ divide: x multiplyMoles unknown

X multiply

Remember…Divide to dig down to Mr. Mole

Go across the mole bridgeClimb back up by multiplying

What mass of carbon dioxide is produced when 50.0 grams of butane (C4H10) is burned in excess oxygen gas?

2 C4H10 + 13 O2 → 8 CO2 + 10 H2 O

Step 1 Write balanced equation.

Step 2 Place boxes for given and desired amounts under appropriate chemicals.

50.0 g C4H10 ____ g CO2

Step 3 Draw an arrow from given amount down to moles box. Convert to moles by dividing by molar mass. On this chart all down arrows require divide . Dig down to Mr. Mole.

.8621 mol C4H10

÷ 58.0 g/mol

Step 4 Draw mole bridge from known moles to unknown moles box. Place coefficients of known and unknown on bridge. Divide by known and multiply by unknown to find unknown moles.

÷ 2 : x 83.4483 mol CO2

x 44.0 g/mol

Step 5 Convert to moles of unknown by multiplying by molar mass of unknown.

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