Question

when tap water contains high levels of calcium, a substance called calcium carbonate (caco₃) can build up at the mouths of water faucets. this buildup, called limescale, can prevent water from flowing through a faucet properly. to remove the calcium carbonate, you can scrub the faucet with citric acid (c₆h₈o₇). citric acid combines with calcium carbonate to form calcium citrate (ca₃c₁₂h₁₀o₁₄), carbon dioxide gas (co₂), and water (h₂o). the calcium citrate washes away easily, allowing water to flow through the faucet again. complete the table to classify the substances in this chemical reaction.

substance	reactant	product
calcium citrate (ca₃c₁₂h₁₀o₁₄)	□	□
carbon dioxide (co₂)	□	□
citric acid (c₆h₈o₇)	□	□
water (h₂o)	□	□

Explanation:

Step1: Identify Reactants and Products

From the problem, the reaction is: Citric acid ($\ce{C6H8O7}$) combines with calcium carbonate ($\ce{CaCO3}$) to form calcium citrate ($\ce{Ca3C12H10O14}$), carbon dioxide ($\ce{CO2}$), and water ($\ce{H2O}$). So reactants are substances that react (citric acid and calcium carbonate), products are substances formed (calcium citrate, carbon dioxide, water).

Step2: Classify Each Substance

• Calcium carbonate ($\ce{CaCO3}$): Reactant (part of what reacts)
• Calcium citrate ($\ce{Ca3C12H10O14}$): Product (formed)
• Carbon dioxide ($\ce{CO2}$): Product (formed)
• Citric acid ($\ce{C6H8O7}$): Reactant (part of what reacts)
• Water ($\ce{H2O}$): Product (formed)

Answer:

Substance	Reactant	Product
calcium citrate ($\ce{Ca3C12H10O14}$)		$\boldsymbol{\checkmark}$
carbon dioxide ($\ce{CO2}$)		$\boldsymbol{\checkmark}$
citric acid ($\ce{C6H8O7}$)	$\boldsymbol{\checkmark}$
water ($\ce{H2O}$)		$\boldsymbol{\checkmark}$