The decomposition looks like this. 225.0 mL of 2.30 M HCl is 0.518 mole of HCl. I know this confuses some people. MgCO3 + 2HCl --> H2CO3 + MgCl2. The Morton Salt company adopted the slogan "When it rains it pours" with reference to the fact that its MgCO 3-containing salt would not stick together in humid weather. MgCO3 + 2 HCl --> MgCl2 + CO2 + H2O. The catch is that H2CO3 (carbonic acid) molecules don't exist in aqueous solution, so it is questionable whether they actually every form in the first place. Put them both together and we have your reaction. 100.0 mL of 2.45 M MgCO3 is 0.245 mole of MgCO3. MgCO3(s) + 2HNO3(aq) → Mg(NO3)2(aq) + CO2(g) + H2O(l) It's Mg(NO3)2 (and not MgNO3) because the magnesium ion has a charge of +2, and so you need two nitrate ions to equalize the charge (because NO3 ions only have a charge of -1). H2CO3 --> CO2 + H2O. 2HCl + MgCO3 --> MgCl2 + CO2 + H2O. KMnO 4 + HCl = KCl + MnCl 2 + H 2 O + Cl 2; K 4 Fe(CN) 6 + H 2 SO 4 + H 2 O = K 2 SO 4 + FeSO 4 + (NH 4) 2 SO 4 + CO; ... Give us feedback about your experience with chemical equation balancer. Because of its low solubility in water and hygroscopic properties, MgCO 3 was first added to salt in 1911 to make it flow more freely. Since two mole of HCl may completely react with one mole of MgCO3, 0.245 mole of MgCO3 is the limiting reactant.