# We can work on Chemistry

1) An excavator is preparing to dig a basement for a new house. Part of his contract reads that he must dispose of all the dirt he removes while digging the basement in an EPA approved landfill. He will dig a hole that is 40.0 feet wide by 80.0 feet long and 7.5 feet deep. He first uses his shovel and scoops up 1.00 kg of dirt, and then determines that the dirt has a volume of 600 cm3. The excavator knows that his dump truck can only carry 8,000 kg of dirt. How many dump-truck loads will it take to haul the dirt away?

(1 in = 2.54 cm) __ dump-truck loads

My answer: 88.49 not correct

2) Phosphorus reacts with iodine as shown in the chemical reac on below. What is the percent yield of the reac on if 42.33g PI3 is obtained from the reac on of 48.0 g of I2 with excess phosphorus?

2P(s) + 3I2(s) â 2PI3(s) _% Yield

My answer: 92.49% not correct

3) Determine the oxidation number of each of the element P in H2PO3-?

My answer: +3 not correct

4) The residential rate for natural gas is about \$15 per thousand cubic foot. Burning one cubic foot of natural gas releases about 1080 kJ of heat. How much would it cost to heat the water in a 25,000 gallon swimming pool from 52Â°F to 78Â°F, assuming all of the heat from burning the natural gas went towards warming the water? (1 gal = 3.785 L; the specific heat of water = 4.184 J/gÂ·Â°C) \$

My answer: \$3.18 not correct

5) When an automobile engine starts, the metal parts immediately begin to absorb heat released during the combus on of gasoline. How much heat will be absorbed by a 165 kg iron engine block as the temperature rises from 15.7Â°C to 95.7Â°C? (The specific heat of iron is 0.489 J/gÂ·Â°C.) _____kJ

My answer: 6,450 not correct

6) At body temperature 2,404 joules of energy are required to evaporate 1.00 g of water. A er vigorous exercise, a person feels chilly because the body is giving up heat to evaporate the perspira on. A typical person perspires 25 mL of water a er 20. minutes of exercise. How much body heat is this person using to evaporate this water? ______kJ

My answer: 60.1 not correct

7) On a spring morning (15.Â°C) you fill your res to a pressure of 32psi atmospheres. As you ride along, the re heats up to 45Â°C from the friction on the road. What is the pressure in your res now in units of atmospheres? _______atm

My answer: 2.4 not correct

8) Ammonium nitrite undergoes decomposi on to produce only gases as shown below.

NH4NO2(s) â N2(g) + 2H2O(g)
How many liters of gas will be produced by the decompositon of 32.0 g of NH4NO2 at 525Â°C and 1.5 atm? __ L (N2 + H2O)

My answer: 21.84 not correct

9) In an effort to address concerns about global warming, a power plant in Portland,Oregon is designed to take all of its exhaust gases from its boilers and recycle the CO2 using the Solvay process to make sodium hydrogen carbonate. The reac on is shown below.

NH3(g) + H2O(l) + CO2(g) + NaCl(aq) â NaHCO3(aq) + NH4Cl(aq)
How many liters each of NH3 and CO2 (both at STP) would be consumed to produce 6.00 kg of sodium bicarbonate?
The volume of both NH3 and CO2 would be ______liters

My answer: 800 not correct

10) Baking powder is made up of sodium hydrogen carbonate and calcium hydrogen phosphate. When baking powder is wet, these components react to produce carbon dioxide. The equation for this reaction is given below.

NaHCO3(aq) + CaHPO4(aq) â NaCaPO4(aq) + CO2(g) + H2O(l)

Assuming all of the carbon dioxide was released as a gas, how many liters of CO2(g) would be formed at room temperature from 4.00 g of NaHCO3 and excess CaHPO4?
Approximately _____liters

Sample Solution

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