CHEMICAL PROPERTIES OF ACID

A student adds dilute hydrochloric acid to powdered zinc carbonate in a test tube. Which of the following observations correctly identifies the products?

• Effervescence is observed, forming hydrogen gas and zinc chloride solution

• White precipitate forms, producing carbon dioxide and zinc hydroxide solution

• Effervescence is observed, forming carbon dioxide gas and zinc chloride solution

• No reaction occurs because zinc carbonate is insoluble in water

Which statement explains why an acid reacts with both magnesium metal and magnesium carbonate but produces different gases in each case?

• Both reactions produce hydrogen gas because magnesium is reactive

• Acid reacts with magnesium to release hydrogen gas, while it reacts with magnesium carbonate to release carbon dioxide gas

• Acids only react with carbonates to produce hydrogen gas

• The gas produced depends on whether the acid used is strong or weak

A student mixes dilute sulfuric acid with an unknown metal carbonate. The reaction produces gas bubbles and a salt solution. Which test would best confirm that the gas is carbon dioxide?

• Expose the gas to burning splint – it pops

• Bubble the gas through limewater – it turns cloudy

• Smell the gas – it has a pungent odor

• Hold blue litmus paper in the gas – it turns red

Which balanced chemical equation correctly represents the reaction of nitric acid with calcium carbonate?

• HNO₃ + CaCO₃ → Ca(NO₃)₂ + H₂

• 2HNO₃ + CaCO₃ → Ca(NO₃)₂ + H₂O + CO₂

• HNO₃ + CaCO₃ → Ca(NO₃)₂ + CO₂

• HNO₃ + CaCO₃ → Ca(NO₃)₂ + H₂O

A student adds excess zinc metal to dilute hydrochloric acid. After some time, no more bubbles are seen. Which conclusion is most accurate?

• The acid has been neutralised completely

• Zinc has stopped reacting because hydrogen displaced it

• Zinc has stopped reacting because hydrogen displaced it

• All the hydrochloric acid has been used up, leaving excess zinc