Mass, Volume & Applied Density Problems

Consider the plot of Metal A (Blue) and Metal B (Red). Determine the density of Metal B (Red) from the plot to the correct sig. figs. and correct units!

• 8.46 g/mL

• 2.43 g/mL

• 7.64 g/mL

• 6.21 g/mL

Answer explanation

The best fit line for the Metal B (red) passes through zero. Use (0,0) as one of the points for calculating slope, then choose a POINT on the line (as far away from the origin as possible) that intersect with two gridlines; example, (26.0,220.0). Slope = (220.0-0)/(26.0-0) = 8.46 g/mL. NOTE: Only 3 sig. figs. The slope for the Metal A (blue)  is written to 3 sig. figs. and both are on the same plot...so they both must have the same number of significant figures.

Consider the plot of Metal A (Blue) and Metal B (Red). What is the density of Metal A (Blue) from the plot to the correct sig. figs.

• 6.21 g/mL

• 8.46 g/mL

• 2.43 g/mL

• 7.64 g/mL

Answer explanation

The slope of a mass vs volume is the density for the metal. The slope of the line for the Metal A (Blue) is 2.43 g/mL, so that is the density for Metal A (Blue)

Illustrate equal volume cubes of Metal A (2.43 g/mL) and Metal B (8.46 g/mL) by drawing circular particles in labeled boxes). If the box for Metal A has 4 particles in it. How many particles should be drawn in the same size box (same volume) for Metal B.

• 3

• 4

• 7

• 14

Answer explanation

Because mass and density are DIRECTLY PROPORTIONAL (at constant volume) a simple ratio can be used to solve for the count of particles or "mass" for the metal B.

 $\frac{8.46\ \frac{g}{mL}}{2.43\ \frac{g}{mL}}=\frac{?}{4\ of\ A}$  $\rightarrow$ so the ? =13.9 particles or about 14

You have a piece of iron wire (7.87 g/mL), a piece of copper wire (8.96 g/mL) and a piece of titanium wire (4.54 g/mL).

All 3 pieces of wire are the SAME MASS and diameter but different lengths.

Which wire is the SHORTEST of the 3?

JUST put the name of the element in the blank!

Answer explanation

density and volume are inversely proportional. The wire with the LARGEST density will have the SMALLEST volume (for the same amount of mass)...and vice versa, the wire with the SMALLEST density will have the LARGEST volume for (for the same amount of mass).

What is the volume of Object X ?

• 10.0 cm³

• 15.0 cm³

• 20.0 cm³

• 25.0 cm³

What is the measurement using the correct number of sig. figs.?

• 89cm

• 88.9cm

• 88.90cm

• 88cm

Answer explanation

The smallest clearly marked (certain) division is in the TENTHS place, so the length MUST be estimated and reported to the HUNDREDTHS place (one decimal place to the right of the smallest clearly marked division) even if the measurement is "exactly on the line"

What is the reading of the meniscus?

• 35mL

• 45mL

• 35.0mL

• 30.5mL

Answer explanation

The smallest clearly marked (certain) division is in the ONES place, so the volume MUST be estimated and reported to the TENTHS place (one decimal place to the right of the smallest clearly marked division) even if the measurement is "exactly on the line"

Put the liquids in order from most dense to least dense?

• 4, 3, 2, 1
• 1, 2, 3, 4
• 3, 4, 2, 1, 
• 4, 3, 1, 2

Tags

NGSS.5-PS1-3

Jack has a rock. The rock has a mass of 14g and a volume of 2cm³. What is the density of the rock?

• 7 mL

• 7 g/cm³

• 28 g/cm³

• 0.14 g/cm³

Answer explanation

$Density\ =\frac{mass}{volume}$

If an object has a density of 3.6 g/mL and you put it into water, will it sink or float?

• sink

• float

Answer explanation

You are required to know that the density of water at room temperature and pressure is 1.0 g/mL. An object with a density greater than 1.0 g/mL will sink in water.