Molarity and Solution Stoichiometry

Manuel measures out 36 grams of sodium on a scale. How many atoms of sodium are in his sample?

• 9.43 x 10²³ atoms

• 5.49 x 10²³ atoms

• 7.02 x 10²³ atoms

• 6.02 x 10²³ atoms

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NGSS.HS-PS1-7

The idea that the number of atoms of molecules in a substance is proportional to its physical mass is accredited to-

• Amedeo Avogadro

• Timothy Taiwo

• Jorge Hernandez

• Keisha Vigil

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NGSS.HS-PS1-7

What is the molarity of a 0.5L sample of a solution that contains 60.0 g of sodium hydroxide (NaOH)

• 0.8 M

• 1.5M

• 3.0M

• 6.0M

How many mL of 0.5M HNO₃ would be needed to react with 85mL of 0.75M KOH?

• 127.5mL

• 0.1275mL

• 31.9mL

• 0.031875mL

What would the molarity of the solution be if 0.475 mol of KNO₃ were formed in this reaction and the final volume of the solution was 595mL

• 0.798M

• 1.25M

• 282.6M

• 7.98x10^-4M

Molarity is:

• moles per liter of solution

• written with a unit of M

• calculated by dividing the moles of a substance by the liters of solvent

• all of the above

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NGSS.HS-PS1-5

Calcium carbonate reacts with aqueous hydrochloric acid to form calcium chloride solution, water, and carbon dioxide gas in the following equation: CaCO₃ (s) + 2 HCl --> CaCl₂ (aq) + H₂O (l) + CO₂ (g) What volume (in mL) of 1.35 M HCl will be needed to completely react with 3.82 g of solid CaCO₃?

• 56.5 mL

• 47.2 mL

• 61.6 mL

• 34.7 mL

• 124 mL

Solid iron (II) sulfide reacts with hydrochloric acid to form hydrogen sulfide gas and aqueous iron (II) chloride: FeS (s) + 2 HCl (aq) --> H2S (g) + FeCl2 (aq) If 145 mL of HCl is needed to completely react with 25 g of iron (II) sulfide, what is the concentration of the HCl solution?

• 3.1 M

• 0.68 M

• 2.7 M

• 9.0M

• 3.9 M

What is the molarity of a solution prepared by dissolving 5.0 moles of solute in 2.5 liters of solution?

• A) 0.5 M

• B) 1.0 M

• C) 2.0 M

• D) 2.5 M

Which of the following statements about molarity is true?

• A) It is the number of moles of solute per kilogram of solvent.

• B) It is the number of moles of solute per liter of solution.

• C) It is the number of grams of solute per liter of solution.

• D) It is the number of grams of solute per kilogram of solvent.

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NGSS.HS-PS1-5