Heating carbonates sim

What the sim shows

A metal carbonate breaks up on heating into the metal oxide and carbon dioxide, MCO₃ → MO + CO₂, and the carbon dioxide turns limewater milky. The more reactive the metal, the harder its carbonate is to break up: thermal stability runs the opposite way to reactivity. Potassium and sodium carbonates do not break up in a Bunsen flame at all, and calcium carbonate needs a far higher temperature than a boiling tube reaches: its carbon dioxide pressure at 700 °C is only about 0.06 atm, so it stops breaking up once the gas in the tube holds that share of carbon dioxide. Copper(II) carbonate turns from green to black copper(II) oxide; zinc oxide is yellow while hot and white when cold. The first bubbles are only air, pushed out as the tube warms. Before turning off the burner, lift the delivery tube out of the limewater: as the tube cools, the gas inside shrinks and would pull cold limewater back onto the hot glass (suck-back), which can crack it. The tube is clamped with its mouth a little lower than its closed end, so that any water that condenses near the mouth cannot run back onto the hot glass. Each run uses 1.00 g of carbonate and the gas-tests figure's limewater, 5 cm³ of 0.02 mol/dm³ calcium hydroxide, which counts as milky once 1.2 cm³ of carbon dioxide has reacted; bubbles of carbon dioxide give it up to the limewater at most 0.3 cm³ a second, and the rest passes through. The temperatures at which the carbonates break up are approximate data-book values; how hot the Bunsen gets the powder (about 700 °C) and how fast each carbonate breaks up are this figure's estimates, so the times are a guide, not a measurement. The green powder sold as copper(II) carbonate is really basic copper(II) carbonate, CuCO₃·Cu(OH)₂, which gives off water as well. Keep bubbling and the milkiness clears again, as soluble calcium hydrogencarbonate forms, so lift the tube out as soon as it turns milky. The clock runs 10 times faster than real time for the first minute, then 30 times, and only 1 times while the limewater is milky.

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