BYU Chem 41 Final Exam Questions With
Verified Answers
In which of the following examples does a physical change occur?
A silver bowl tarnishes.
A peach spoils.
A bracelet turns your wrist green.
A glue gun melts a glue stick. - answer✔A glue gun melts a glue stick.
What are the products in the following equation?
2Al + 6HCl → 2AlCl3 + 3H2
AlCl3 and HCl
Al and HCl
Al and H2
AlCl3 and H2 - answer✔AlCl3 and H2
Which of the following is a homogeneous mixture?
Italian salad dressing
vegetable soup
granite
saltwater - answer✔saltwater
When a student burns a piece of magnesium, he sees a bright light and is left with a new
powdery substance. What has this student observed?
a precipitation process
a chemical change
a physical change
the filtration technique - answer✔a chemical change
Which of the following is a heterogeneous mixture?
sucrose
a gold ring
seawater
granite - answer✔granite
Chemical energy in a battery turns into electrical energy in a radio, which turns into mechanical
energy as sound waves bombard your eardrums and enable you to hear the radio. Why does
this happen?
- because of the law of conservation of mass-energy, which tells us that the amount of mass
that was used from the battery was traveling at the speed of light, and because E=mc2, the
mass turned into the exact amount of energy that bombarded your eardrums
- because of the law of definite proportions, which tells us that the proportion of battery
chemicals always comes in whole number proportions
- because of the law of conservation of energy, which tells us that the amount of energy that
was used from the battery is the same amount of energy that reached your eardrums
- because of the law of conservation of mass, which tells us that the mass of the part of the
battery that was used is the same as the mass of the soun - answer✔- because of the law of
conservation of energy, which tells us that the amount of energy that was used from the
battery is the same amount of energy that reached your eardrums
Which of the following statements is true of mass?
The mass of an object can be found by comparing its weight to an object whose mass is known.
The mass of an object depends on the force of gravity acting on it.
Mass is expressed in pounds or Newtons.
Mass is usually measured with a spring scale. - answer✔The mass of an object can be found by
comparing its weight to an object whose mass is known.
Is iron rusting a physical or a chemical change?
a physical change
a chemical change - answer✔a chemical change
If your weight on earth is 107 pounds and the force of gravity on the sun is 27 times the gravity
of the earth, what would your weight be on the sun?
394 pounds
2889 pounds
71 pounds
3.96 pounds - answer✔2889 pounds
A student places ink on filter paper and puts it in a beaker of alcohol. The ink travels across the
filter paper. This is an example of what kind of separation technique?
crystallization
distillation
chromatography
filtration - answer✔chromatography
According to the law of conservation of mass, how much HCl is consumed in the following
reaction?
(32 g) + (?) → (64 g) + (18 g)
2Al + 6HCl → 2AlCl3 + 3H2
82 g
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