## Chem – College: Unit Conversions

What sections should I know before attempting to learn this section?

We want to use the units and ratios we discussed in the previous section as mathematical tools for conversions. I will show you how to do one example problem of each of the three ratio techniques.  Keep the unit prefixes table open as you are following the problems below.

VIDEO Advanced Unit Conversions Solving Demonstrated Example 1: If you have 1200 ng how many kg is that? (using only the base to decimal ratio)

Step 1:

What numbers and units does the question give you?

Step 2:

What units does the question ask for?

Step 3:

How do we start laying out the problem?

Answer: Put the numbers and units given by the question first.

 1200 ng 1

Step 4:

What comes next?

 1200 ng kg 1

Step 5:

What is the first ratio I put between them?

 1200 ng g kg ng

Step 6:

Fill in the numbers and cross out units

 1200 ng 0.000 000 001 g kg 1 ng

Step 7:

What is the second ratio?

 1200 ng 0.000 000 001 g kg kg 1 ng g

Step 8:

Fill in the numbers and cross out units

 1200 ng 0.000 000 001 g 1 kg = kg 1 ng 1000 g

Step 9:

How do I complete the math?

Answer: (1200 * 0.000 000 001) / 1000 = 0.000 000 0012

 1200 0.000 000 001 1 kg = kg 1 1000

Step 10:

COMPLETE ANSWER: 0.000 000 0012 kg or 1.2 * 10-9 kg

VIDEO Advanced Unit Conversions Solving Demonstrated Example 2: If you have 134 cm how many Mm is that? (using only the power of 10 ratio)

Step 1:

What numbers and units does the question give you?

Step 2:

What units does the question ask for?

Step 3:

How do we start laying out the problem?

Answer: Put the numbers and units given by the question first.

 134 cm 1

Step 4:

What comes next?

 134 cm Mm 1

Step 5:

What is the first ratio I put between them?

 134 cm m Mm cm

Step 6:

Fill in the numbers and cross out units.

 134 cm 10-2 m Mm 1 cm

Step 7:

What is the second ratio?

 134 cm 10-2 m Mm Mm 1 cm m

Step 8:

Fill in the numbers and cross out units.

 134 cm 10-2 m 1 Mm Mm 1 cm 106 m

Step 9:

How do I complete the math?

Answer: (134 * 10-2) / 106 = 0.000 00134

 134 10-2 1 Mm = Mm 1 106

Step 10:

COMPLETE ANSWER: 0.000 00134 Mm or 1.34 * 10-6 Mm

VIDEO Advanced Unit Conversions Solving Demonstrated Example 3: If you have 369GL then how many pL is that? (using only the common ratio)

Step 1:

What numbers and units does the question give you?

Step 2:

What units does the question ask for?

Step 3:

How do we start laying out the problem?

Answer: Put the numbers and units given by the question first.

 369 GL 1

Step 4:

What comes next?

 369 GL pL 1

Step 5:

What is the first ratio I put between them?

 369 GL L pL GL

Step 6:

Fill in the numbers and cross out units.

 369 GL 1 000 000 000 L pL 1 GL

Step 7:

What is the second ratio?

 369 GL 1 000 000 000 L pL pL 1 GL L

Step 8:

Fill in the numbers and cross out units.

 369 GL 1 000 000 000 L 1 000 000 000 000 pL = pL 1 GL 1 L

Step 9:

How do I complete the math?

Answer: (369 * 1 000 000 000 * 1 000 000 000 000) = 3.69 *1023

 369 1 000 000 000 1 000 000 000 000 pL= pL 1 1

Step 10:

COMPLETE ANSWER: 3.69 * 1023 pL

PRACTICE PROBLEMS: Give the final answer for these questions.  Use unit prefixes table if you need.

If you have 15 dag how many cg is that?

If you have 27 um how many cm is that?

How many kilograms are in 49 dg?

How many megameters are in 98 hm?  