Lab quiz

Last week we learned that certain solutions make a light bulb light up. Give a specific example of one such solution and explain the chemistry behind why.

• HCl is a strong acid so the molecule dissociates when it goes into solution. This does not break up into ions. This causes a strong electrolyte because HCl is a strong acid.

• HCl is a strong acid so the molecule dissociates when it goes into solution. This causes it to break up into ions. This causes a strong electrolyte because HCl is a strong acid.

• HCl is a weak acid so the molecule dissociates when it goes into solution. This causes it to break up into ions. This causes a strong electrolyte because HCl is a weak acid.

Classify each of the following compounds/substances as either a strong electrolyte, a weak electrolyte, or a non-electrolyte.

a. Sodium chloride (NaCl)

b. Glucose/sugar (C6H12O6)

c. Ammonia (NH3)

• a. Non-electrolyte

  b. Weak electrolyte

  c. Strong electrolyte

• 
  a. Weak electrolyte

  b. Non-electrolyte

  c. Strong electrolyte

• a. Strong electrolyte

  b. Non-electrolyte

  c. Weak electrolyte

Last week, we learned that not all compounds dissociate to the same degree, varying the way they conduct electricity.

1st- Choose the formula that does not dissociate completely

A. HI (hydroiodic acid) B. NH3 (ammonia) C. NaOH (sodium hydroxide)

2nd- What is the compound called in terms of its conductivity in solution?

• b.

  a non-electrolyte

• a.

  a weak electrolte

• b.

  a weak electrolyte

• a.

  a strong electrolyte

Give an example of a compound or substance that is insoluble in water

• sugar is insoluble in water, they do not remain separate when mixed

• salt is insoluble in water, they remain separate when mixed

• Oil is insoluble in water, they remain separate when mixed

If 3 grams of calcium sulfate (136.14 g/mol) is dissolved in enough water to make 150 mL of solution, what is the molarity of the solution?

• 15 M

• 28 M

• 0.15 M

• 0.28 M

Sugar is added to a cup of coffee. The sugar would be the _

• Solute

• Solvent

• Titrant

• Analyte

What is the most correct piece of glassware that you should use to transfer a sample of your stock solution into a volumetric flask for dilution?

• Graduated cylinder

• Beaker

• Erlenmeyer flask

• Volumetric pipette

If 4.5 mL of 1.0 M NH4Cl is used, to what volume does it need to be diluted to make a 0.25 M solution?

• 18 L

• 9 mL

• 18 mL

• 9L

You perform a titration between Sodium Hydroxide (NaOH) and Hydrochloric Acid (HCl). NaOH is in the burette and the HCL is in the Erlenmeyer flask. If 3.0 mL of 0.5 M NaOH was added to 100 mL of HCl to reach the endpoint, what is the concentration of the HCl?

• 0.015 M

• 15 M

• 0.036 M

• 36 M

If 4 grams of copper sulfate (159.609 g/mol) is dissolved in enough water to make 100 mL of solution, what is the molarity of the solution?

• 25 M

• 0.18 M

• 0.25 M

• 18 M