User: When magnesium carbonate, MgCO2, reacts with nitric acid, HNO3, it forms magnesium nitrate, Mg(NO3)2, and carbonic acid, H2CO3. Carbonic acid then breaks down into water and carbon dioxide. Which two types of reactions take place in this process? A. synthesis and decomposition B. single-replacement and combustion C. double-replacement and decomposition D. double-replacement and combustion

Weegy: C. double-replacement and decomposition
Auto answered|Score .6|cha97mw|Points 1097|

User: For the chemical reaction C2H6 + 137 kJ ? C2H4 + H2, the chemical energy of the A. reactant is greater than the chemical energy of the products. B. products is greater than the chemical energy of the reactant. C. reactant and the chemical energy of the products are equal. D. reaction is conserved.

Weegy: B. [ products is greater than the chemical energy of the reactant. moles = mass / molar mass moles HBr = 186 g / 80.908 g/mol = 2.3 moles TRUE C2H6 + 137 kJ - - -> C2H4 + H2 You can see that the energy (137 kJ) is on the reactant side of the equation. So you have to put energy into the reaction to to form the prodicts. Therefore the products must have a higher energy then the reactants = B ]
Expert answered|dennis003|Points 170|