Chapter 0 (Introduction) Notes/Questions/Answers
Know the
difference between solids, liquids, gases;
F=m*a; W=F*d.
Energy- capacity to do work;
-kinetic
energy- energy due to motion; Ek=1/2 mv2
-potential
energy- energy due to position; Ep=mgh
Etotal= Ek+Ep; Etotal is constant if forces act on
the body, can convert Ek to Ep and vice versa
Pressure-measured in pascals (Pa); F/A= 1 N/1
m2=1 kg/m*s2
1 atm =
1.013 bar; 1 bar = 105 Pa;
Questions/Answers
0.3)
Calculate the work that a person of mass 65 kg must do to climb between two
floors of a building separated by 4.0 m.
W=F*d=(65
kg* 9.8 m/s2) * (4.0 m) = 2600
J
0.5) A car of mass 1.5 t (1 t = 103 kg) travelling
at 50 km h−1 must be brought to a stop. How much kinetic energy must be
dissipated?
KE= ½mv2= ½(1.5 t)(103
kg/t)(50km/hr)(1 hr/3600 s)(1000 m/1km)= 14.9
kJ
0.8)
Calculate the minimum energy that a bird of mass 25 g must expend in order to
reach a height of 50 m.
PE=mgh=(.025
kg)(9.8 m/s2)(50m)=12 J
0.12) Express (a) 108 kPa in torr, (b) 0.975 bar in atmospheres,
(c) 22.5 kPa in atmospheres, (d) 770 Torr in pascals.
a.) (108
kPa)(.007501 torr/1 Pa)(1000 Pa/1 kPa)=810
torr
b.)(.975
bar)(1 atm/1.013 bar)= 0.962 atm
c.)
(22.5kPa)(1000Pa/1 kPa)(1 bar/105 Pa)(1 atm/1.013 bar)= 0.222 atm
d.) (770
torr)(1 Pa/0.007501 torr)=1.03*105 Pa
0.13)
Calculate the pressure in the Mindañao trench, near the Philippines, the
deepest region of the oceans. Take the depth there as 11.5 km and for the
average mass density of sea water use 1.10 g cm−3.
(11.5
km)(1000 m/km)(1.1g/cm3)(1kg/1000g)(100 cm/1m)^3(9.8m/s2)=
1.24*108 Pa
0.18)
Given that the Celsius and Fahrenheit temperature scales are related by qCelsius/°C
= (qFahrenheit/°F − 32), what is the temperature of absolute zero (T =
0) on the Fahrenheit scale?
At
absolute 0, K=0; C=K-273=0-273=-273; C=(f-32)/1.8; -273=(f-32)/1.8= -459.67 °F
0.24) The
molar mass of the oxygen-storage protein myoglobin is 16.1 kg mol−1. How many
myoglobin molecules are present in 1.0 g of the compound?
(1.0 g)(1
mole/16100 g)(6.02*1023 molecules/mole)= 3.74*1019 molecules
0.28) What
mass of sodium chloride should be dissolved in enough water to make 300 cm3 of
1.00 M NaCl(aq)?
Molarity=
moles/Liters; 1.00 M= moles/((300 cm3)(1 mL/1 cm3)(1
L/1000 mL))=0.3 moles;
0.3
moles=grams/molar mass; 0.3 moles= grams/(58.443 g/mol)= 17.5 g
0.30)
Calculate the mole fractions of the molecules of a mixture that contains 56 g
of benzene and 120 g of methylbenzene (toluene).
Moles of
benzene= (56 g)(1 mole/78.118 g)=.717 mol
Moles of
toluene= (120 g)(1 mole/92.138 g)= 1.3 mol
Xbenzene=moles
benzene/moles total=.717/(1.3+.717)= .35
Xtoluene=moles
toluene/moles total=1.3/(1.3+.717)= .64
