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To find enthalpy changes of the following reactions.
2A(g)
2B(g)
∆ = 120Kj
B(g)
A(g)
∆ =-60Kj
A(g)
C(s)
∆ =-170Kj
17. amount of carbon in 40.0kg of anthracite.
1 mole of the sample =3083g/mol
Grams in the sampe=40*1000=40000g
%carbon content is 92.1%, so the amount in the sample is
0.921*40= 36.84kg
16. The molar mass of methanol is 32grams
32grams produces 764Kj
So, 35.81grams will produce 855kj.
35.81 grams.
15.The formation of 51.0g of O2 results in the absorption of 438kJ of heat.
14. when 1.60mol of H2 reacts, 387kj is released.
13. all statements are true except, when energy is transferred as heat from the surrounding to the
system, ∆H is negative.
12. specific heat= number of joules used/(∆temperature*grams)
305J/(∆temperature change*37.6g)=0.128J
∆temperature*37.6=2382.8125
∆temperature change=63.3727
So final temperature is 20.0+63.3727=83.37.
11.heat energy = (specific heat capacity)*(∆temperature change*grams)
=(1.75)*(168*2430)=714420J
10.heat energy = (specific heat capacity)*(∆temperature change*grams)
263J=(0.903)*(22.5*grams of sample
22.5*grams =180.509
Grams=8.0226g
9. mass=24.5g,temperature change =15.7,heat energy=90.4J.
Specific heat capacity=90.4/(15.7*24.5)=0.235
Hence, silver is the answer.
8. grams=21.59g, heat energy used=1435J,final temperature=181.5 C.
Temperature change=154.4
Specifc heat capacity=1435/(154.4*21.59)=0.43047J/(g.C)
7. The amount of heat required to increase the temperature of 1g of a substance by 1 0C.
3. Endothermic
exothermic
Making popcorn in a microwave
a burning match
Boiling water
The reaction inside a chemical pack
Burning rocket fuel.
6. To convert the following energy units.
1kj=0.239kilocalorie
13kj=3107.075 calories.
123kcal=514.632kj
5. a) 938kj=938000j
b)2530kcal=10585.52kj
c)6.27*10^6j=1498.565kcal
2. Classify the following phase changes as endothermic or exothermic.
Endothermic
exothermic
Solid to liquid
liquid to solid
Liquid to gas
gas to liquid
Solid to gas
gas to solid
1.Classify each point with correct information about kinetic energy and potential energy.
A=max PE,min KE B=max KE, min PE
C=max PE, min KE.
Which of the following represents kinetic energy?
Wind, riding a bicycle, an apple falling from a tree.
14. If 506mol of octane combusts, what volume of carbon dioxide is produced at 38.C and 0.995 atm.
Forever 2 moles of octane you have, you get 16 moles of CO2. So divide 506 moles of octane by two,
and then multiply by 16 to find the number of moles of carbon dioxide.
Number of moles of CO2=4048
Use the equation PV = nRT, or Pressure x Volume = moles x R x Temperature (in Kelvin)
.995 atm x V = number of CO2 moles x .08206 x 311
V=(4048*0.08206*311)/0.995=103826.766cm3=0.1038L
12. first we need to compute moles of each gas
Moles of Argon=3.04/39.95=0.0761
Moles of Krypton=1.12/85=0.0132
Pressure acted by Argon, P(Ar)=nRT/V=[(0.0761)(0.08206)(298)]/(2.50)=0.744 atm
Pressure acted by Krypton, P(Kr)=nRt/V=[(0.0132)(0.08206)(298)]/(2.50)=0.129 atm
Total pressure acted=0.744+0.129=0.873 atm.
13.
Pressure acted by a third gas=[(0.200)(0.08206)(304)]/(9.30)=0.536 atm
P(total)=P1 + P2 +P3= 0.244+0.540+0.536=1.32 atm.
9.
PV=nRT, T=PV/nR.[(0.039610)(0.08206)(T)]/(887.1*10^-3)=0.96 atm.
T= 0.96/(3.66407*10^-3)=262K
T=262-253= 90 C.
8.
Directly proportional
P and n
inversely proportional
P and V
V and n
P and T
T and V
P and V
5. The volume of a fixed amount of gas is directly proportional to its absolute temperature.
4. Pressure is inversely proportional to volume, so P1V1/T1=P2V2/T2
P2=(PIV1T2)/(T1V2)=(1.14*2.30*304)/(2.90*10^2*1.03)=2.668 atm.
7.
Volume is directly proportional to the number of moles.
V and n (directly proportional). Initial number of moles n1=(32.4*331.8*10^-3)/4.265L= 2.52
moles.
An ideal gas in a sealed container has an initial volume of 2.35L. At constant pressure, it is cooled to
24.00 degrees, where its final volume is 1.75L. what is the initial temperature?
V1/T1=V2/T2, T1=(V1T2)/V2=(2.35*297)/1.75=398.83K= 125.80C
1. To label the curve, starting from the origin, solid only, solid and liquid, liquid only, liquid and
gas, gas only. In that order.
4. volume of a gas is directly proportional, so PIV1=P2V2, P2=(P1V1)/V2=(5.31*2.84)/5.22=2.89
atm.
3. If the pressure in the manometer was equal to atmospheric, h would be 0.0
The gas pressure is 773-55=718mm.
5. q=mc*temperature change=(2.55*1000*168*1.75)=749700J.
2. 1520mmHg,1.5 atm, 494mmHg, 0.25 atm.(from highest to lowest).
3. To start, you will need the equation q=∆Hvap(mass/molecular mass). You can also convert to
moles first. So using the values you provided:
3.02g*(1/18.01)*(40.66)=6.82Kj
4. molar mass of ethanol=46grams
Molar heat of vaporization=38.6kj/mol
Therefore (241.8/38.6)moles require 241.8kj.
6.2642moles, requires 241.8kj
The number of gram heated is(6.2642*46)=288.155g.
7. which molecules can hydrogen bond?
H2 and HF
8. Cl2 exhibits only London dispersion because it's nonpolar, all the rest are polar
6. only NF3 and CIF have polar interactions.
9. H2O hydrogen bonding ,CH3Cl and CO Dipole dipole and dispersion,H2 Dispersion only
11. CH3OH,CH3CI, CH4 (from the highest boiling point to the lowest boiling point)
10. Hydrogen bonding, London Dispersion Forces, and Dipole-Dipole interactions
2. density-determines if a substance floats or sinks, relates a mass to its volume, is a physical
property.
12. CH4, CH3CI, CH3OH.(from highest vapor to lowest)
11. P(total)=P1+P2+P3, Partial pressure of Ne=11.3-(4.15+1.36)=5.79 atm.