AP Chem

What volume of a 0.100MHCl stock solution should be used to prepare 250.00mL of 0.0250MHCl?

• 1.00mL

• 16.0mL

• 62.5mL

• 100.mL

A 500.mL aqueous solution of Na₃PO₄ (molarmass=164g/mol) was prepared using 82gof the solute. What is the molarity of Na₃PO4 in the resulting solution?

• 0.0010M

• 0.16M

• 0.25M

• 1.0M

How many grams of NaCl (molarmass=58g/mol) are needed to prepare 100.mL of a 0.25M NaCl solution?

• 0.23g

• 0.43g

• 0.67g

• 1.5g

When methanol and water are mixed together, they form a homogeneous mixture. Based on the information in the table above, which of the following would be the best procedure for separating a mixture of methanol and water?

• Filtration

• Distillation

• Paper chromatography

• Column chromatography

Which of the following methods is most appropriate to use to determine the number of different-colored components in a sample of black ink?

• Distillation at atmospheric pressure

• Elemental analysis to determine the mass ratio of C:H:N:O

• Column chromatography using a nonpolar stationary phase and water as the mobile phase

• Paper chromatography using different solvents with a range of polarities as the mobile phase

The diagram above shows thin-layer chromatograms of the same mixture of two compounds. Based on the chromatograms, which solvent would be most effective at separating the two compounds if the same stationary phase is used for column chromatography?

• Solvent A

• Solvent B

• Solvent C

• Solvent D

Tags

NGSS.HS-ETS1-3

Methanol, CH3OH, dissolves completely in water to form a solution that does not conduct electricity. Which of the following diagrams best shows the major type of attractive force that exists between the particles in the solution?

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Tags

NGSS.HS-PS1-3

A student adds a 1g sample of an unknown, brittle solid to distilled water, stirs the mixture, and then measures its conductivity. The student repeats this procedure with more samples of the unknown solid and then produces the graph above. Which of the following statements about the graph and the properties of the solid is correct?

• The increase in conductivity indicates that the unknown is an ionic solid that dissociates into ions when it dissolves in water

• The increase in conductivity indicates that the unknown is a network covalent solid that ionizes in water

• The straight line plot indicates that the unknown solid is infinitely soluble in water

• The straight line plot indicates that the unknown solid has a very low solubility in water.

Tags

NGSS.HS-PS1-3

Which of the diagrams above best represents the interactions that are responsible for the relatively large solubility of KCl crystals in water, and why?

• Diagram 1, because strong ion-dipole interactions between KCl and water help to dissociate the solute

• Diagram 1, because strong London dispersion forces between the K⁺ and Cl⁻ ions and water replace the weak London dispersion forces between two water molecules.

• Diagram 2, because strong dipole-dipole forces between KCl and water help to separate the KCl units within the crystals.

• Diagram 2, because the hydrogen bonds between water molecules expand to accommodate the KCl particles and pull them into solution.

How much of the 12.0 M stock solution do you need to prepare 250 mls of .20M HCl?

• 15,000 mls
• 4.17 mls
• 9.6 mls
• 0.0096 mls