1 2Mg + o2 --> 2Mgo
2 MgCo3 --> MgO + Co2
3 Co2 + Ca(OH)2 --> CaCo3 + h2O
4 Zn + 2HCl --> ZnCl2 + H2
5 2H2 + O2 ---> 2H2O
2 KI + Pb(NO3)2 --> 2KNO3 + PbI2
endothermic is absorbs energy.
exothermic is releases energy.
which of those reaction are endothermic?
which of those reaction are exothermic?
To determine whether a reaction is endothermic or exothermic, we need to look at the overall energy change of the reaction. If the reaction absorbs energy, it is endothermic, and if it releases energy, it is exothermic.
Let's analyze each of the given reactions:
1) 2Mg + O2 -> 2MgO
This reaction involves the combination of magnesium (Mg) with oxygen (O2) to form magnesium oxide (MgO). Since the reaction results in the formation of a new compound and releases energy in the form of heat and light, it is exothermic.
2) 2MgCO3 -> 2MgO + CO2
This reaction involves the decomposition of magnesium carbonate (MgCO3) into magnesium oxide (MgO) and carbon dioxide (CO2). Similar to the first reaction, this reaction also releases energy in the form of heat and light. Therefore, it is also exothermic.
3) 3CO2 + Ca(OH)2 -> CaCO3 + H2O
This reaction involves the combination of carbon dioxide (CO2) with calcium hydroxide (Ca(OH)2) to form calcium carbonate (CaCO3) and water (H2O). In this reaction, energy is released during the formation of the new compounds, making it exothermic.
4) Zn + 2HCl -> ZnCl2 + H2
This reaction involves the reaction of zinc (Zn) with hydrochloric acid (HCl) to form zinc chloride (ZnCl2) and hydrogen gas (H2). Similar to the previous reactions, energy is released during the formation of the new compounds, indicating that this reaction is also exothermic.
5) 2H2 + O2 -> 2H2O
This reaction involves the combination of hydrogen gas (H2) with oxygen gas (O2) to form water (H2O). The breaking of the chemical bonds in hydrogen and oxygen requires an input of energy, which makes this reaction endothermic.
6) 2KI + Pb(NO3)2 -> 2KNO3 + PbI2
This reaction involves the double displacement reaction between potassium iodide (KI) and lead(II) nitrate (Pb(NO3)2) to form potassium nitrate (KNO3) and lead iodide (PbI2). Energy is released during the formation of the new compounds, making this reaction exothermic.
Therefore, the endothermic reaction is reaction number 5 (2H2 + O2 -> 2H2O), and the exothermic reactions are 1, 2, 3, 4, and 6.