Answers Practice Test 115 Lab Test 1 (first half) PDF

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Answers Practice Test 115 Lab Test 1 (first half), for chemistry 115 lab test, practice test answer...

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Lab Test One Practice Test CHE 115L

1. How many significant figures are contained in each of the following numbers? a. 20034.660 8 b. 0.000000000748 3 c. 90001. 5 d. 2. 1 2. Perform the following calculations and report your answer to the correct number of significant figures or decimal places. 20.86= 20.9 a. 1.400 + 0.56 + 18.9 = b. (0.0756) × (130) = 9.828 = 9.8 c. 130.01 + 2.89 = 132.9 = 132.90 This one has the added zero because you cannot get rid of a significant figure you have to have the same number of sig-figs as the least number of sig-figs in the original numbers. 3. Perform the following calculations and report your answer with proper units AND correct number of significant figures or decimal places. a. 64.927 g – 51.677 g = 13.25 = 13.250g This one has the added zero because you can not get rid of a significant figure you have to have the same number of sig-figs as the least number of sig-figs in the original numbers. b. 9.230 g ÷ 7.21 mL =

1.28016644 = 1.28 g/mL

c. 3.25 cm × 0.18 cm × 1.70 cm =

0.9945 = 0.99 cm3

4. Give the following measurements with the correct number of significant figures.

1.35cm b.

a.

c.

55.5mL

d.

23.9mL or 24.0mL

25.65cm

*Remember the last place is estimated and can be different- pay attention to number of decimal places answer is read to 5. Find the density of the following unknown objects A. Mass: 4.513g Volume: 2.52 mL Density: 1.79 g/mL Math: (4.513g)/(2.52 mL) = 1.79 g/mL B. Mass: 13.169 g Length: 3.629 cm Width: 0.650 cm Height: 3.932 cm Density: 1.42 g/cm^3 Math: (13.169g)/(3.629cm*0.650cm*3.932cm) g/cm^3 6. Using the chart below find what the two unknow objects are using he density. Aerogel Coal Cork Gallium Magnesium Wax

.16mg/mL 1.42 g/mL 0.24 g/mL 5.9 g/mL 1.74 g/mL 1.8 g/mL

.16mg/cm^3 1.42 g/cm^3 0.24 g/cm^3 5.9 g/cm^3 1.74 g/cm^3 1.8 g/cm^3

A. Wax B. Coal 7.We know that carbohydrates and proteins typically supply 4kcal of energy per gram and fats supply 9kcal of energy per gram. Using this information, calculate the number of Food Calories in a Tix Bar if it contains 12 g of fat, 2 g of protein, and 34 g of carbohydrates. Fat- 12g x 9kcal= 108 kcal Protein- 2g x 4kcl= 8 kcal Carbohydrates- 34g x 4kcal= 136 kcal Total food calories- 252 Food Calories 1 Food Calorie = 1kcal=1000cal

8. Find the heat absorbed by the water and the energy content of the following food. Heat Absorbed= q=m  tCp Energy Content= kcal/g Mass of the food burned: 0.32g Mass of the water: 50.35g Temperature change: 40.5 C Heat Absorbed: 2039.174 cal 2.039174 kcal Energy Content: 6.38 kcal/g

Math: Heat absorbed (50.35g) *(40.5 C)*(1.0 cal/gC) = 2039.174 cal=2040cal / 1000 = 2.04kcal Energy Content: (2.04 kcal)/ (0.32g)= 6.38 kcal/g 9. Give the characteristics of alpha, beta, and gamma radiation. Radiation Alpha Beta Gamma

Charge 2+ -1 0

Mass 4 amu 0 amu O amu

Type Charged protons and neutrons (He) High energy Electrons High Energy Light

10. List the types of Radiation from most penetrating to least penetrating 1. Gamma 2. Beta 3. Alpha

11. How would you separate the following items from a mixture? What properties are you using to separate these items? Salt- the solubility properties of the salt, the salt dissolves in the water separating it from the rest of the mixture. The water can then be evaporated out later.

Sand- The size of the sand can be filtered out of the solution with the water and a pieces of filter paper.

Styrofoam- There are many ways that this can be done, the most common is to pick out the Styrofoam due to its size. Another way to remove the Styrofoam is using the static electricity. Iron- The magnetic properties of the iron make easy removal by the use of a magnet.

12. Calculate percent recovery. . Calculate percent recovery. Starting mass: 10.00g Recovered mass of materials: Sugar: 2.56g Aluminum: 1.69g Sand: 3.52g Beans: 2.90g Total Recovered mas: 10.67 Percent Recovery: 106.7% Math: Total mass (2.56+1.69+3.52+2.90) =10.67 Percent recovery (10.67/10.00) = 1.067*100= 106.7%

13.How do the following affect the rate of a reaction? Surface Area: The change in the surface area can change the amount of area the particles in the solution have to collide with the surface are of the solid. Temperature: The rise and fall in the temperature can change the amount of energy in the particles have when they collide with each other. A higher temperature the more energy the lower temperature the less energy. Catalyst: A catalyst is added to a mixture to complete a reaction quickly by lowering the activation energy needed to complete a reaction. Concentration: The change the number of particles that are there to collide with each other. The more the mixture is concentrated the more the collisions.

14. What would happen to the rate of the reaction if the following was applied to the reaction? a. The temperature is raised. The reaction rate would rise, and the reaction time would decrease b. The antacid is crushed before being mixed before the acid is mixed in. The reaction rate would rise, and the reaction time would decrease c. If a student added double the amount of starch solution to the iron mixture The reaction rate would rise, and the reaction time would decrease d. If a catalyst was added into a mixture. The reaction rate would rise, and the reaction time would decrease 15. Determine the half life of the sample based on the figure bellow.

Decay 60 50

CPM

40 30 20 10 0

0

2

4

6

8

Minutes

10

12

14

16

2.0-3.0 minutes depending on how you estimate Identify the functional groups on the molecules below

For letters a-c. name the organic molecules a.1-pentanoic acid b.propanoic acid c.1- propanamine...