Chemistry

Provide suitable responses to the problems shown below. Where applicable, show your work to receive full credit. Late assignments will be assessed a penalty of 5% of the overall grade per day late.

1. (a) How much work is done by a person who exerts a constant force of 65.5 Newtons on a wheelchair at 45.0o above the horizontal, and pushes the wheelchair 15.5 meters? (b) Convert the amount of work from joules to kilocalories. Show your work and report your answers to 3 significant figures. (6 pts)
2. Calculate the force in Newtons needed to lift a 121-lb object vertically against gravity. Note that g = 9.8 m/s2 and 1 lb = 0.4535 kg. Show your work and report your answers to 3 significant figures. (3 pts)
3. How much work in Joules is required to lift the object described in the previous question 3.00 ft (see question 2)? Note that 1 m = 3.281 ft. Show your work and report your answers to 3 significant figures. (3 pts)
4. Calculate the power that is required to perform the work from the previous problem in exactly 6.00 seconds (see question 3). Show your work and report your answers to 3 significant figures. (3 pts)
5. Calculate the amount of work that is done if a gas expands from 2.50 L to 5.75 L against a constant force of 885 Pascals? Note: 1 m3 = 1000 L. Show your work and report your answers to 3 significant figures. (4 pts)

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1. Calculate the kinetic energy of an object that has a mass of 275 kg and travelling at a velocity of 15.0 m/s. Show your work and report your answers to 3 significant figures. (4 pts)
2. (a) If a net force of 70.0 N is applied to a 135 kg object to move it 25.0 meters, calculate the work (energy) that was needed to move the object. (b) How fast did the object move?
   Show your work and report your answers to 3 significant figures. (6 pts)
3. An object of unknown mass sitting 20.0 feet above the ground is known to have a potential energy of 164 J. Calculate the mass of the object in kilograms. Note 1 m = 3.281 ft. Show your work and report your answers to 3 significant figures. (4 pts)
4. Decide whether entropy is increasing or decreasing for each of the following processes: (3 pts)

(a) Subliming solid iodine, I2:

(b) N2(g) + 3H2(g)  2NH3(g)

1. (a) Calculate the work done by a gas in a cylinder if the gas absorbs 4.50 joules of heat (Q) and expands to a volume of 0.0010 m³ against a constant pressure of 475 Pa.
   (b) Use U = Q + W to calculate the internal energy of the gas. Show your work and report your answers to 3 significant figures. (4 pts)

Sample Solution