# Density, Conversions, and Significant Figures

1. a: A cube of osmium metal 1.500cm on a side has a mass of 76.31 g at 25*C. What is its density in g / cm3 at this temperature?

B: The density of titanium metal is 4.51 g / m3 at 25*C. What mass of titanium displaces 65.8 mL of water at 25*?

C: The density of bezene at 15 *C is 0.8787 g / mL. Calculate the mass of 0.1500 L of benzene at this temperature.

Solutions for a,b,c

A. g/cm3

B. g

C. g

2, A cylindrical rod formed from silicon is 16.8 cm long and has a mass of 2.17 kg. The density of silicon is 2.33 g / cm3. What is the diameter of the cylinder? (the volume of a cylinder is given by TTr2h, where r is the radius and h is its length.)

Solution:

_________________________________________cm

Question 3: Indicate the number of significant figures in each of the following measure quanties.

A: 3.7745km___________________________

B: 205 m2 ___________________________

C: 1.700cm____________________________

D: 350.0 K _____________________________

E: 307.080 g ___________________________

Question 4. Carry out the following conversions

A: 0.105 in_______________________________mm

B: 0.870 qt_______________________________mL

C: 9.75 um/s______________________________km/hr

D: 4.733 yd3_______________________________m3

E: $3.99/lb_________________________________dollars per kg

F 8.75 lb/ft3_________________________________g/ml

Solutions

5. Carry out the following operations and express the answer with the appropriate number of signigicant figures.

A: 320.55 - (6104.5/2.3)

B: [(285.3 x 105) - (1.200) x 103] x 2.8954

C: (0.0045 x 20, 000.0) + (2813 x 12)

D: 863 x [1255 - (3.45 x 108)]

6.The concentration of carbon monoxide in an urban apartment is 48 ug/m3. What mass of a carbon monoxide in grams is present in a room measuring 9.0 x 14.5 x 18.8ft?

Solution

______

_________________________________g

7. By using estimation techniques determine which of the following is the heaviest and which is the lightest.

Quantity Conversion factor(s) Conversion to grams

5-lb bag of potatoes g potatoes

5-kg bag of sugar g sugar

1 gal of water (density = 1.0g/ml) g water

Solution

8.The liquid substances mercury (density = 13.5 g / mL), water (1.00 g / ml ), and cyclohexane

(0.778 g / mL) don not form a solution when mixed, but separate in distinct layers. Sketch how the liquids would position themselves in a test tude.

Question 9. Small spheres of equal mass are made of lead (density = 11.3 g / m3),

Silver (10.5 g / m3) and aluminum (2.70 g / m3). Which sphere has the largest diameter and which has the smallest?

Spheres:

Lead (cm) Pb sphere

Silver (cm) Pb sphere

Aluminum (cm) Pb sphere

Solutions

Question 10. Automobile batteries contain sulfuric acid, which is commonly referred to as "batter acid". Calculate the number of grams of sulfuric acid in 0.500 L of battery acid if the solution has a density of 1.28 g / mL and is 38.1% sulfuric acid by mass.

________________________________________________ g H2SO4 ( . 5L)

solution

https://brainmass.com/chemistry/physical-chemistry/density-conversions-and-significant-figures-249753

#### Solution Summary

This solution explains:

1) How to solve for density, mass, and volume using the density equation.

2) How to determine the number of significant figures in a number.

3) How to convert quantities using the factor-label method

4) How to perform mathematical operations using sigfigs.

Measurements and the Process of Science

Learning Plan 1. Measurements and the Process of Science

Target Competency

1. Apply basic chemistry methods and measurements. (Ch.1)

Directions

Part A.

Choose something to observe in your environment (e.g., sugar dissolving in Kool Aid, pasta cooking, alka seltzer dissolving in water, vinegar reacting with baking soda, etc.).

Make a list of all the observations you can make (at least 10).

Now, from this list of observations, come up with a hypothesis that you can test.

Design an experiment that could be run to test your hypothesis.

Be sure to follow the steps of the scientific method in setting up your experimental report.

You do not need to perform the experiment. You will be graded on your initial observations, hypothesis and written experimental report.

Part B.

a. If we assume the density of blood is 1.060 g/mL, what is the mass of 6.56 pints of blood in grams?

b. A patient weighs 146 pounds and is to receive a drug at a dosage of 45.0 mg per kg of body weight.

The drug is supplied as a solution that contains 25.0 mg of drug per mL of solution.

How many mL of the drug should the patient receive?

c. A typical aspirin tablet contains 5.00 grains of pure aspirin analgesic compound. The rest of the tablet is starch. How many aspirin tablets can be made from 50.0 g of pure aspirin?

d. What Fahrenheit temperature corresponds to 37.0 degrees C?

e. If a person smokes 10.0 packs of cigarettes a week and each cigarette contains 5.00 mg of tar, how many weeks will she have to smoke to inhale 0.250 pounds of tar? [Use: 20 cigarettes = 1 pack]

f. A patient needs 0.300 g of a solid drug preparation per day. How many 10.0 mg tablets must be given to the patient per day?

Part C

In two paragraphs, discuss the terms precision and accuracy in relation to significant digits.

In your discussion, address how significant digits relate to the measuring device, and why rules for significant digits are needed for calculations involving measurements.

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