Question

Which one is an endothermic reaction?

A. Carbon with oxygen

B. Baking soda with citric acid

C. Sodium with water

D. Magnesium with oxygen​

Answer 1

Answer :

A. Carbon with oxygen

Explanation 1 : (Reason)

Here ;

A. [Reason] When you burn carbon in oxygen, that is the energy which is causing the surroundings to get hotter. And here is an endothermic change - In this case, 178 kJ of heat are absorbed when 1 mole of calcium carbonate reacts to give 1 mole of calcium oxide and 1 mole of carbon dioxide. This is an endothermic reaction.

B. [Reason] The reaction between citric acid and baking soda had a negative at value. The reaction is an endothermic reaction because it takes in energy in form of heat. This is known because the temperature decreased as the reaction took in heat. Secondly, the baking soda has dissolved into the solution, forming new products. This is an exothermic reaction.

C. [Reason] A colourless solution is formed, consisting of strongly alkalic sodium hydroxide (caustic soda) and hydrogen gas. This is an exothermic reaction.

D. [Reason] Magnesium gives up two electrons to oxygen atoms to form this powdery product. This is an exothermic reaction.

Explanation 2 : (Definition)

Endothermic reactions are chemical reactions in which the reactants absorb heat energy from the surroundings to form products.

Endothermic reactions generally involve the formation of chemical bonds through the absorption of heat from the surroundings.

Hope it helps :)