Download presentation

Presentation is loading. Please wait.

Published byJessica Blake Modified over 4 years ago

2
The relationship between temperature and volume

3
If we place a balloon in liquid nitrogen it shrinks: How Volume Varies With Temperature So, gases shrink if cooled. Conversely, if we heat a gas it expands (as in a hot air balloon). Lets take a closer look at temperature before we try to find the exact relationship of V vs. T.

4
No. 68 F (20 C) is not double 50 F (10 C) Yes. 44 lb (20 kg) is double 22 lb (10 kg) Whats the difference? Weights (kg or lb) have a minimum value of 0. But the smallest temperature is not 0 C. We saw that doubling P yields half the V. Yet, to investigate the effect of doubling temp- erature, we first have to know what that means. An experiment with a fixed volume of gas in a cylinder will reveal the relationship of V vs. T… Temperature scales Is 20 C twice as hot as 10 C? Is 20 kg twice as heavy as 10 kg?

5
Temperature vs. Volume Graph (fig.7,8 pg.430) 5 10 15 20 25 30 Volume (mL) Temperature ( C) 0 100 – 273 25 mL at 22C 31.6 mL, 23.1 mL Y=0.0847x + 23.137

6
If a volume vs. temperature graph is plotted for gases, most lines can be interpolated so that when volume is 0 the temperature is -273 C. Naturally, gases dont really reach a 0 volume, but the spaces between molecules approach 0. At this point all molecular movement stops. –273 C is known as absolute zero (no E K ) Lord Kelvin suggested that a reasonable temp- erature scale should start at a true zero value. He kept the convenient units of C, but started at absolute zero. Thus, K = C + 273. 62 C = ? K: K= C+273 = 62 + 273 = 335 K Notice that kelvin is represented as K not K. The Kelvin Temperature Scale

7
What is the approximate temperature for absolute zero in degrees Celsius and kelvin? Calculate the missing temperatures 0 C = _______ K100 C = _______ K 100 K = _______ C – 30 C= _______ K 300 K = _______ C 403 K = _______ C 25 C = _______ K0 K = _______ C Kelvin Practice 273373 – 173243 27130 298 – 273 Absolute zero is – 273 C or 0 K

8
Looking back at the temperature vs. volume graph, notice that there is a direct relationship. It can be shown that V/T = constant Read pages 432-3. Answer these questions: 1.Give Charless law in words & as an equation. Charless Law: as the temperature of a gas increases, the volume increases proportionally, provided that the pressure and amount of gas remain constant, V 1 /T 1 = V 2 /T 2 Charless Law

9
2.A sample of gas occupies 3.5 L at 300 K. What volume will it occupy at 200 K? 3.If a 1 L balloon is heated from 22°C to 100°C, what will its new volume be? 4.Do questions 16, 17, 19 on page 434 V 1 = 3.5 L, T 1 = 300K, V 2 = ?, T 2 = 200K Using Charles law: V 1 /T 1 = V 2 /T 2 3.5 L / 300 K = V 2 / 200 K V 2 = (3.5 L/300 K) x (200 K) = 2.3 L V 1 = 1 L, T 1 = 22°C = 295 K V 2 = ?, T 2 = 100 °C = 373 K V 1 /T 1 = V 2 /T 2, 1 L / 295 K = V 2 / 373 K V 2 = (1 L/295 K) x (373 K) = 1.26 L For more lessons, visit www.chalkbored.com www.chalkbored.com

Similar presentations

OK

Section 9.2. Definition: a measure of the average kinetic energy of a substance’s particles Generally measured in o C The Kelvin temperature scale.

Section 9.2. Definition: a measure of the average kinetic energy of a substance’s particles Generally measured in o C The Kelvin temperature scale.

© 2018 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google