Scientific Tutor
Chem – College: Unit Conversions
Author: Andrew
What sections should I know before attempting to learn this section?
—> Introduction to Problem Solving
What about more advanced metric unit conversions?
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?
Answer: 1200 ng
Step 2:
What units does the question ask for?
Answer: kg
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?
Answer: The units of the answer.
| 1200 ng | kg | ||
| 1 |
Step 5:
What is the first ratio I put between them?
Answer: 0.000 000 001 g / 1 ng, start with units.
| 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?
Answer: 1000 g / 1 kg, start with units.
| 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?
Answer: 134 cm
Step 2:
What units does the question ask for?
Answer: Mm
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?
Answer: The units of the answer.
| 134 cm | Mm | ||
| 1 |
Step 5:
What is the first ratio I put between them?
Answer: 10-2 m / 1 cm, start with units.
| 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?
Answer: 106 m / 1 Mm, start with units.
| 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?
Answer: 369GL
Step 2:
What units does the question ask for?
Answer: pL
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?
Answer: The units of the answer.
| 369 GL | pL | ||
| 1 |
Step 5:
What is the first ratio I put between them?
Answer: 1 000 000 000 L / 1 GL, start with units.
| 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?
Answer: 1 000 000 000 000 pL / 1 L, start with units.
| 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?
Answer: 15000 cg
If you have 27 um how many cm is that?
Answer: 0.0027 cm
How many kilograms are in 49 dg?
Answer: 0.0049 kg
How many megameters are in 98 hm?
Answer: 0.0098 hm
When you finish the lesson, try out the metrics and conversions worksheet.
Posted in Chemistry
