ALEKS TEST PREPARATION GUIDE WITH
CORRECT ANSWERS
●● Sample B is a solid yellow cube with a total mass of
50.0g
. The cube is ground to a fine orange powder and added to a 500mL
beaker full of water. The beaker is stirred vigorously. Some of orange
powder settles to the bottom of the beaker, and some rises to the top and
floats on the water. When the powder at both the bottom and the top of
the beaker is filtered out, dried, and weighed, the total mass is measured
to be 50.1g.
Is sample B made from a pure substance or a mixture?
Answer: mixture
●● Write the chemical symbols for three different atomic cations that all
have
5
protons.
Answer: B+3, B+2, B+5
●● Write the chemical symbols for three different atomic anions that all
have
,17
protons.
Answer: Cl-,Cl-4, Cl-2
●● Sample A is a solid yellow cube with a total mass of
50.0g
. The cube is put into a beaker filled with 250.mL of water. The cube
collapses into a small pile of orange powder at the bottom of the beaker.
When this powder is filtered out, dried and weighed, it has a total mass
of 29.9g. If the experiment is repeated with 500.mL of water, the powder
that's left over has a mass of 30.0g.
Pure substance or mixture?
Answer: Mixture
●● Sample B is
100.g
of a coarse grey powder with a faint unpleasant smell. 15.g of the
powder are dissolved in ethanol. 0.5mg of the resulting black solution is
carefully dropped onto a thick sheet of paper laid flat in a tray. After 30
minutes the initial round black stain has spread out and faded in color to
a deep purple.
Answer: Can't decide
, ●● Sample A is a solid yellow cube with a total mass of
50.0g
. The cube is divided into two smaller 25.0g subsamples, and the
minimum volume of water needed to dissolve each subsample is
measured. The first subsample just barely dissolved in 101.mL of water,
the second in 92.mL. When the experiment is repeated with a new 50.0g.
sample, the minimum volume of water required to dissolve the two
subsamples is 89.mL and 93.mL.
Answer: mixture
●● Sample B is
100.mL
of a clear liquid. The density of the liquid is measured, and turns out to
be 0.77/gmL. The liquid is then cooled in the refrigerator. At 10.0°C
crystals begin to appear until the liquid is about half crystal, half liquid.
After 30 minutes, no more crystals appear, even though the temperature
is lowered to 6.3°C.
Answer: Mixture
●● Sample A is
100.mL
of a clear liquid. The liquid is heated in a flask until it boils, which starts
to happen at 66.2°C. As the liquid boils, the temperature continues to
rise, until the last of the liquid boils away at 76.0°C.
Answer: Mixture
CORRECT ANSWERS
●● Sample B is a solid yellow cube with a total mass of
50.0g
. The cube is ground to a fine orange powder and added to a 500mL
beaker full of water. The beaker is stirred vigorously. Some of orange
powder settles to the bottom of the beaker, and some rises to the top and
floats on the water. When the powder at both the bottom and the top of
the beaker is filtered out, dried, and weighed, the total mass is measured
to be 50.1g.
Is sample B made from a pure substance or a mixture?
Answer: mixture
●● Write the chemical symbols for three different atomic cations that all
have
5
protons.
Answer: B+3, B+2, B+5
●● Write the chemical symbols for three different atomic anions that all
have
,17
protons.
Answer: Cl-,Cl-4, Cl-2
●● Sample A is a solid yellow cube with a total mass of
50.0g
. The cube is put into a beaker filled with 250.mL of water. The cube
collapses into a small pile of orange powder at the bottom of the beaker.
When this powder is filtered out, dried and weighed, it has a total mass
of 29.9g. If the experiment is repeated with 500.mL of water, the powder
that's left over has a mass of 30.0g.
Pure substance or mixture?
Answer: Mixture
●● Sample B is
100.g
of a coarse grey powder with a faint unpleasant smell. 15.g of the
powder are dissolved in ethanol. 0.5mg of the resulting black solution is
carefully dropped onto a thick sheet of paper laid flat in a tray. After 30
minutes the initial round black stain has spread out and faded in color to
a deep purple.
Answer: Can't decide
, ●● Sample A is a solid yellow cube with a total mass of
50.0g
. The cube is divided into two smaller 25.0g subsamples, and the
minimum volume of water needed to dissolve each subsample is
measured. The first subsample just barely dissolved in 101.mL of water,
the second in 92.mL. When the experiment is repeated with a new 50.0g.
sample, the minimum volume of water required to dissolve the two
subsamples is 89.mL and 93.mL.
Answer: mixture
●● Sample B is
100.mL
of a clear liquid. The density of the liquid is measured, and turns out to
be 0.77/gmL. The liquid is then cooled in the refrigerator. At 10.0°C
crystals begin to appear until the liquid is about half crystal, half liquid.
After 30 minutes, no more crystals appear, even though the temperature
is lowered to 6.3°C.
Answer: Mixture
●● Sample A is
100.mL
of a clear liquid. The liquid is heated in a flask until it boils, which starts
to happen at 66.2°C. As the liquid boils, the temperature continues to
rise, until the last of the liquid boils away at 76.0°C.
Answer: Mixture
