Solutions and States of Matter
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AP Chemistry › Solutions and States of Matter
Which of the following would most likely form a homogeneous solution?
Water and benzene (C6H6)
NaNO3 and octanol (C8H18O)
NH4Cl and water
A and B
All would form homogeneous solutions
Explanation
Like dissolves like. The NH4Cl and water mixture involves an ionic solid and a polar solvent. Examples a and b involve mixing polar/non-polar solvents and ionic and non-polar solvents.
Under which conditions would you expect Ar to deviate the most from ideal behavior?
200 K and 1 atm
200 K and 10 atm
300K and 5 atm
300K and 10 atm
Ar always behaves ideally
Explanation
The ideal gas law assumes the gas particles are non-interacting and small relative to the size of their container. At 200K (lowest temperature in the list, and the highest pressure). This gives Ar the most time to interact due to molecular speeds and the high pressure implies the molecular size is not insignificant relative to the container.
When does a gas behave most like an ideal gas?
At low temperatures, low volume, low intermolecular interactions
At high temperatures, high volume, low intermolecular interactions
At low volumes, high temperatures, and high intermolecular interactions
At high temperature, high volumes, and high intermolecular interactions
At low temperatures, high volume, and low intermolecular interactions
Explanation
The ideal gas law assumes the gas particles are non-interacting and small relative to the size of their container. At high temperatures the gas molecules are moving fast enough to shorten the time scale for any interactions. At high volumes, the molecular size becomes small relative to the size of the container, and the low interactions mean the molecules act more independently.
Would you expect a polar or non polar gas to deviate most from ideal gas behavior?
Non polar gases, because of high dispersion interactions
Polar gases, because of high dipole-dipole interactions
Non polar gases because of reduced overall intermolecular forces
Polar gases because of hydrogen bonding
Both polar and non polar gases behave ideally
Explanation
Polar gases would have increased interactions due to their dipoles that would lead to deviations from ideal gas behavior.
Which of the following would most likely form a homogeneous solution?
Water and benzene (C6H6)
NaNO3 and octanol (C8H18O)
NH4Cl and water
A and B
All would form homogeneous solutions
Explanation
Like dissolves like. The NH4Cl and water mixture involves an ionic solid and a polar solvent. Examples a and b involve mixing polar/non-polar solvents and ionic and non-polar solvents.
Which of the following will be the precipitate in the following reaction?
2KCl + Ca(OH)2 → 2KOH + CaCl2
Ca
Ca(OH)2
KOH
CaCl2
No precipitate forms
Explanation
Though the solubility of calcium hydroxide, Ca(OH)2, is fairly low, it is a reactant and will not form a precipitate. The solid calcium hydroxide will be added to an aqueous solution of potassium chloride, KCl. During the reaction, the calcium hydroxide will transition to potassium hydroxide (KOH) and calcium chloride (CaCl2), both of which are completely soluble. At the end of the reaction, no precipitate will be observed.
What photon wavelength can promote a transition from the n = 1 (ground state) to the n = 3 (excited state)?
204 nm
306 nm
102 nm
408 nm
1 m
Explanation
Which of the following compounds is insoluble in water?
Explanation
Unless paired with an alkali metal, carbonate compounds are generally insoluble. Compounds that contain nitrate or an alkali metal will generally be soluble in water, and hydroxides are soluble when paired with heavier alkaline earth metals (such as calcium).
Calculate the molar solubility of AgBr in 0.050 M AgNO3 at room temperature. The Ksp of AgBr is 5.4 x 10-13.
1.08 x 10-11 M
2.16 x 10-11 M
1.08 M
2.16 M
1.57 x 10-12 M
Explanation
Which of the following compounds is insoluble in water?
Explanation
Unless paired with an alkali metal, carbonate compounds are generally insoluble. Compounds that contain nitrate or an alkali metal will generally be soluble in water, and hydroxides are soluble when paired with heavier alkaline earth metals (such as calcium).