1. A. 1.29x10-3 mg/mL, B. 1.29 mg/mL, C. 1.29x10-6 mg/mL
QUESTION:
The density of air is 1.29x10-3 g/L. What is the density of air in mg/mL?
A. 1.29x10-3 mg/mL, B mg/mL, C. 1.29x10-6 mg/mL
The density of air is 1.29x10-3 grams per liter. What is the density of air in milligrams per milliliter?
PAUSE CLICK CONTINUED ON NEXT SLIDE

2. A. 1.29x10-3 mg/mL, B. 1.29 mg/mL, C. 1.29x10-6 mg/mL
QUESTION:
The density of air is 1.29x10-3 g/L. What is the density of air in mg/mL?
A. 1.29x10-3 mg/mL, B mg/mL, C. 1.29x10-6 mg/mL
1 mg
10-3 L
1.29x10-3 g x x
= 1.29x10-3 mg/mL
10-3 g
1 mL L
In this problem, we are asked to change from units without the milli prefix
HIGHLIGHT g and L
to units with a milli prefix.
HIGHLIGHT mg and mL.
By now you should know that milli means 10-3.
This means that 1 milligram is 10-3 grams, and 1 milliliter is 10-3 liters.
So the possible conversion factors that we can use are
HIGHLIGHT 1 mg/10-3 g
1 milligram over 10-3 grams,... or
HIGHLIGHT 10-3 g / 1 mg
10-3 grams over 1 milligrams
and
HIGHLIGHT 1 mL/10-3 L
1 milliliters over 10-3 liters.,... or
HIGHLIGHT 10-3 L / 1 mL
10-3 liters over 1 milliliter
Let’s see which ones we need to use.
First, we write the known amount x10-3 grams
CLICK per liter....
CLICK CLICK
Note that a slash in front of a unit means it’s in the denominator.
Since we want to replace gram by milligram, we use the conversion factor that will allow
us to cancel gram.. Therefore , we use this conversion factor....
HIGHLIGHT 1 mg / 10-3 g
We multiply our known amount...
CLICK
by 1 milligram
over
CLICK grams
The gram unit cancels.
SHOW CANCELLATION OF g units
Next, we multiply by a conversion factor that will allow us to replace Liters by milliliters.
We use this conversion factor....
HIGHLIGHT 1 mL / 10-3 L
The liter unit cancels.
SHOW CANCELLATION OF L units
This gives us an answer of 1.29x10-3 milligrams per milliliters.
We need to express our answer to three significant digits.
since our original quantity has 3 significant digits.
Therefore, the correct answer is A.
PAUSE END RECORDING
1 mg
10-3 g
1 mL
10-3 L
10-3 g
1 mg
10-3 L
1 mL

3. Video ID: 1A-5-5 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08