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. Which are products?