# problem solving PHS

*label*Science

*timer*Asked: Nov 23rd, 2018

*account_balance_wallet*$15

**Question description**

### PLEASE SEE INSTRUCTIONS BELOW Notes for Unit VIII Problem Solving

The following are examples of problems where a student is required
to show work. When working such problems, show as many steps in the
process as possible. It may be helpful to use the examples from the
textbook or the study guide to model your steps. Showing all steps can
help your instructor award partial credit in the event that the overall
answer is incorrect but the work is partially correct. A correct answer
without the demonstration of steps for solving the problem will not
receive full credit.

Example: Place the following two gases in
order of increasing average molecular speed at 300K: H2S and HBr.
Explain your answer.

Correct Way to Solve the Problem:

Since there is a small difference between the average molecular speed
µavg and the root mean squared (rms) speed µrms we can assume that the
following equation is a good reference for determining differences in
µavg

µrms = √(3RT/M)

You will notice that since the
temperature is constant amongst all molecules in the gas phase and the
gas phase constant is, indeed, always constant. Therefore, the only
difference between molecules is their molar mass M. M is in the
denominator so molecules with smaller molar mass (M) will have a higher
molecular speed.

MH2S = 34.08 g/mol

MHBr = 80.91 g/mol

So the series for this answers is:

(slowest) HBr < H2S (fastest)

## Tutor Answer

Attached.

Running Head: UNIT EIGHT WORKSHEET FOR PROBLEM SOLVING

Unit Eight Problem Solving

Student’s Name

Institutional Affiliation

1

UNIT EIGHT WORKSHEET FOR PROBLEM SOLVING

2

This assignment will allow you to demonstrate the following objectives:

•

Describe thermodynamic concepts and their applications.

o Extend the first law of thermodynamics to various daily life activities.

o Identify the maximum efficiency of a heat engine.

o Explain the role of latent heat while phases are changing.

Instructions: Choose 8 of the 10 problems below. Show your work in detail. Answer the

questions directly in this template. Before doing this, it is highly recommending that you

thoroughly review the four examples in the Unit Lesson.

1. The efficiency of a Carnot engine is e=1-Tc/TH, where Tc is a temperature of the cold reservoir

and TH is a temperature of the hot reservoir. What is the condition to have 100% efficiency? Hint:

What is the mathematical condition for Tc/TH to be zero.

An absolute zero condition as the temperature of the cold reservoir remains the only option

to achieve efficiency of 100%. An excellent example of this can be (300 – 0)/300 = 1, in

which 300k is the hot reservoir temperature, and an absolute zero becomes the cold

reservoir temperature. It is only in such an idealized case that an ideal 100 percent

efficiency is possib...

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