H.Chem- 20%- Formative Lab: Evidence of a Chemical Change

Check box ALL of the following that would be considered an indication of a chemical change?

• melting point

• temperature change

• formation of a gas

• production of light

Which of the following best explains the difference between exothermic and endothermic reactions?

• Exothermic reactions release energy, while endothermic reactions absorb energy.

• Exothermic reactions absorb energy, while endothermic reactions release energy.

• Both exothermic and endothermic reactions release energy.

• Both exothermic and endothermic reactions absorb energy.

In the last reaction of this experiment, pieces of aluminum were placed into a solution of copper II chloride, the aluminum seemed to disappear and a brownish solid was formed. What do you think the brownish solid was, and what happened to the aluminum foil?

• The brownish solid was copper, and the aluminum chemically reacted forming aluminum chloride.

• The brownish solid was rust, and the aluminum foil remained unchanged.

• The brownish solid was aluminum oxide, and the aluminum turned into copper.

• The brownish solid was copper chloride, and the aluminum foil formed a protective layer.

Check box all of the following reactions from the lab that were considered a double replacement reaction

• Reaction #1= mixing copper (II) nitrate and sodium hydroxide

• Reaction #2= mixing sodium carbonate and calcium chloride

• Reaction # 5= calcium chloride and water

• Reaction #6= Copper (II) chloride and water

In reaction #6, aluminum pieces were placed in a copper (II) chloride solution. This was considered an ​ (a)   type of reaction with one of the products being ​ (b)  

• copper
• alumium
• chloride
• exothermic
• endothermic

Check box all the following pieces of evidence that would be valid reasons for supporting that reaction #1 was a chemical reaction.

• production of a gas

• permanent change in color

• energy change (heat, light)

• formation of a precipitate

• temperature change

Check box all the following pieces of evidence that would be valid reasons for supporting that reaction #6 was a chemical reaction.

• production of a gas

• permanent change in color

• energy change (heat, light)

• formation of a precipitate

• temperature change

A student was asked to: Identify the type of reaction and balance the equation that would take place between Magnesium metal and phosphoric acid. Which answer below is correct? 

• Single replacement,

  3 Mg +2 H₃PO₄ → 1 Mg₃(PO₄)₂ + 3 H₂

  
  

• Single replacement,

  3 Mg +2 H₃PO₄ → 1 Mg₃(PO₄)₂ + 6 H

• Single replacement,

  3 Mg +2 H₃PO → 1 Mg₃PO₄ + 3 H₂

• Double replacement,

  3 Mg +2 H₃PO₄ → 1 Mg₃(PO₄)₂ + 3 H₂

• Double replacement,

  3 Mg +2 H₃PO₄ → 1 Mg₃(PO₄)₂ + 6 H

A student was asked to: Identify the type of reaction and balance the equation that would take place between cobalt (II) chloride reacts with sodium phosphate Which answer below is correct? 

• Single replacement,
  3 CoCl₂ +2  Na₃PO₄ →

  6 NaCl + 2 Co₃(PO₄)₂

• Single replacement,

  3 CoCl₂ +2 Na₃PO₄ →

  6 NaCl + 1 Co₃(PO₄)₂

• Double replacement,

  3 CoCl₂ +2  Na₃PO₄ →

  6 NaCl + 2 Co₃(PO₄)₂

• Double replacement,

  3 CoCl₂ +2 Na₃PO₄ →

  6 NaCl + 1 Co₃(PO₄)₂

  
  

In a reaction A + B ----> C,  reactant A has 5 g and product C has 9 g. How many grams should reactant B have? (HINT: your answer should have the correct number with proper sig figs and NO UNITS)

Mathematical Equivalence

ON