Chemistry SOL 2001 (Complete)

To remove the sand first and then the salt from a mixture of sand and salt water, one combination of techniques you could use would be to first —

• evaporate and then distill

• evaporate and then condense

• filter and then evaporate

• filter and then condense

Answer explanation

To remove the sand first and then the salt from a mixture of sand and salt water, you would filter to separate the sand, then evaporate the water to obtain the salt.

Which is an example of a synthesis reaction?

• HCl + KOH → KCl + H₂O

• Pb(NO₃)₂ + 2HBr → PbBr₂ + 2HNO₃

• C + O₂ → CO₂

• Mg + H₂SO₄ → MgSO₄ + H₂

Answer explanation

Answer Explanation highlighting the correct choice as a synthesis reaction

3MgO + 2Al → ? What would be the product(s) of this reaction?

• 2Mg₃Al₂O₃

• Mg₃Al₂ + 3O₂

• 6Mg + Al₂O₃

• 3Mg + Al₂O₃

Answer explanation

The correct product of the reaction 3MgO + 2Al is 3Mg + Al₂O₃, as magnesium oxide reacts with aluminum to form magnesium and aluminum oxide.

Tags

NGSS.HS-PS1-7

One of the main assumptions of the kinetic molecular theory of gases is that the particles of an ideal gas—

• must be single atoms instead of molecules

• are in constant motion

• must be maintained at very high pressures

• must be highly chemically reactive

Answer explanation

The correct choice is that the particles of an ideal gas are in constant motion, which is one of the main assumptions of the kinetic molecular theory of gases.

Which is the correct formula for iron (III) sulfate?

• Fe₂(SO₄)₂

• FeSO₄

• Fe₂(SO₄)₃

• Fe₂(SO₃)₃

Answer explanation

The correct formula for iron (III) sulfate is Fe₂(SO₄)₃, where the iron has a +3 charge and combines with three sulfate ions.

Which of these represents the empirical formula and the molecular formula, respectively, for a given organic compound?

• CH and C₂H₂

• CH and CH₄

• CH₂ and C₂H₂

• CH₃ and C₃H₁₂

Answer explanation

The empirical formula represents the simplest whole number ratio of elements in a compound, so CH₃ is the empirical formula. The molecular formula shows the actual number of each element in a compound, so C₃H₁₂ is the molecular formula.

What probably causes water to have the highest specific heat of the substances listed above?

• Molecule size

• Molecular mass

• Strong hydrogen bonds

• High density of ice

Answer explanation

Strong hydrogen bonds are likely the cause of water having the highest specific heat among the substances listed.

Each beaker shown above contains 2.2 grams of iron and 1 liter of 3M H₂SO₄ at STP. Which reaction will go to completion first and why?

• Beaker A because of increased surface area

• Beaker B because of increased surface area

• Beaker A because of a higher concentration level

• Beaker B because of a higher concentration level

Answer explanation

Beaker B because of increased surface area allows for more efficient reaction between iron and H₂SO₄, leading to faster completion.

Tags

NGSS.HS-PS1-5

The element chlorine exists as two naturally occurring isotopes. Cl-35 occurs 75% of the time and Cl-37 occurs 25% of the time. Which of the following calculations should be used to calculate the correct average atomic mass of chlorine?

• (35 amu × .75) + (37 amu × .25)

• (35 amu × 3) + 37 amu / 2

• (35 amu × 3) + 37 amu / 3

• 35 amu + 37 amu / 2

Answer explanation

Choose the calculation (35 amu × 0.75) + (37 amu × 0.25) to find the correct average atomic mass of chlorine.

The average kinetic energy of a sample of water molecules is —

• increased as the temperature is decreased

• increased as the temperature is increased

• unaffected by temperature changes

• always equal to zero

Answer explanation

The average kinetic energy of a sample of water molecules is increased as the temperature is increased.

Tags

NGSS.HS-PS3-2