Week 3 Exercises - Everything you need is in the document PDF

Preview

Summary

Everything you need is in the document...

Description

Week 3 Exercises CHM/110 Version 5

1

University of Phoenix Material Week 3 Exercises Prepare written answers to the following exercises: 1. Write the electronic configurations for the following elements:  Cl -1s22s2 2p63s23p5  Xe -[ Kr ]4d105s25p6  Rb-[ Kr ]5s1 2  Ti -[ Ar ]3d24s 2. Write the Lewis structures for the following compounds:  CH3COOH (carbons are bonded to one another) H

O

|

||

H–C–C–O-H |



H Dichloromethane (CH2Cl2) H



:

:

C Cl Cl Hydrogen peroxide (H2O2) H O O H



Hydrogen cyanide (HCN) H C

N

3. Methane (CH4) behaves as an ideal gas under standard temperature and pressure conditions. What volume is occupied by 1 kg of methane at a temperature of 35 °C and a pressure of 0.9 atm? Mass of CH4 gas = 1kg = 1000g Number of moles of CH4 gas = 1000g x mole/16.0g = 62.5 mole Temperature, T = 35°C =(35 + 273)K =308K Gas consttnat[R]= 0.0821 L atm K-1mol-1 Pressure, P=0.9 atm Use the ideal gas equation to calculate the volume of O2

V =nRT ÷ P = 62.5mole x 0.0821 L x atmK-1 x mol-1 x308K ÷ 0.9atm The volume of the gas is

1756 L

Copyright © 2016 by University of Phoenix. All rights reserved.

Week 3 Exercises CHM/110 Version 5

2

4. How much energy is released when an ice cube tray containing 250 ml of water freezes? The heat of fusion for water is 6.02 kJ/mol. The relationship between specific heat of a substance and heat gained or lost is as follows: Q = n x ΔHfusion Here, n is the number of moles of the substance. The heat of fusion is denoted by ΔHfusion . The volume of water is 250mL. The density of water is 1g/mL. The mass of water is calculated as follows: Mass = Denisty x Volume = 1g/mL x 250mL = 250 g The moles of water are calculated as follows: n=

=

Mass Molar mass 250 g 18 g/mol

=13.89 mol Qenergy released = -n x ΔHfusion = -13.89 mol x 6.02 kJ/mol = −83.62 kJ

Copyright © 2016 by University of Phoenix. All rights reserved....