Heating nitrates sim
Nitrates split three ways on heating.
Heating nitrates · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Nitrates split three ways on heating. Sodium and potassium nitrates melt and give the nitrite and oxygen only: 2NaNO₃ → 2NaNO₂ + O₂, a glowing splint relights and no brown gas is seen. Lithium nitrate is the exception in Group 1: like the middle metals it gives the oxide, 4LiNO₃ → 2Li₂O + 4NO₂ + O₂. The middle metals give the metal oxide, brown nitrogen dioxide and oxygen: 2Cu(NO₃)₂ → 2CuO + 4NO₂ + O₂, the blue solid turning black. Lead(II) nitrate crackles as it is heated, and leaves lead(II) oxide, orange-brown while hot and yellow when cold; zinc oxide is yellow hot and white cold. Silver nitrate goes all the way to silver: 2AgNO₃ → 2Ag + 2NO₂ + O₂. Nitrogen dioxide is a brown, choking, acidic gas: it turns damp blue litmus red. The gas from a middle-metal nitrate still relights a glowing splint although only 1 part in 5 of it is oxygen (less than air): at the hot tip the nitrogen dioxide breaks down and gives more oxygen. Heat nitrates in a fume cupboard. Each run uses 1.00 g; 1.00 g of copper(II) nitrate leaves 0.43 g of copper(II) oxide and gives 255 cm³ of NO₂ and 64 cm³ of O₂ at r.t.p., 319 cm³ in all, counting all the NO₂ as NO₂ as the lesson does (in fact some of it pairs up as colourless N₂O₄ when cool). The temperatures at which the nitrates break up are approximate data-book values, and they are only roughly in the order of the series: what follows the series is how far the break-up goes. How hot the Bunsen gets the powder (about 700 °C), how fast each nitrate breaks up, how brown the gas looks, and the oxygen share that relights a splint (taken as 30%) are this figure's estimates. The copper(II), zinc and magnesium nitrates sold for the lab are hydrated and give off steam before any brown gas; the figure shows the dry salts, as the lesson's sum does. The clock runs 10 times faster than real time for the first minute, then 30 times.
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