Answer:
1=2H₂ + O₂ → 2H₂O
2=CaCo₃ + heat → CaO +CO₂
3=CH₄ + 2O₂ → CO₂ +2H₂O
4=HCl + NaOH → NaCl + H₂O
Explanation:
1 = Simple composition
The formation of water molecule is simple composition reaction. In this reaction two hydrogen atoms react with one oxygen atom and form one water molecules.
2H₂ + O₂ → 2H₂O
The amount of energy released is -285.83 KJ/mol. It is exothermic reaction.
2 = Simple decomposition reaction:
The break down of sodium hydrogen carbonate into sodium carbonate, carbondioxide and water is decomposition reaction. The decomposition reactions re mostly endothermic, because compound required energy to break.
2NaHCO₃ + heat → Na₂CO₃ + H₂O + CO₂
It is endothermic reaction.
Another example is:
CaCo₃ + heat → CaO +CO₂
3 = Combustion reaction
Consider the combustion of methane:
CH₄ + 2O₂ → CO₂ +2H₂O
The burning of methane is exothermic. The combustion reactions are exothermic because when fuel are burns they gives energy.
4 = Neutralization reaction
The neutralization reactions are those in which acid and base react to form the salt and the water. Some neutralization reactions are exothermic because they release heat. e.g
Consider the neutralization reaction of HCl and NaOH.
HCl + NaOH → NaCl + H₂O
Answer:
You first need to construct a balanced chemical equation to describe the reaction:
KOH + HNO3 ---------> KNO3 + H2O
Work out the no. moles of HNO3 being neutralized:
Moles = Volume x Concentration = (25/1000) x 0.0150 = 0.000375 moles
From the balanced equation the molar ratio of KOH to HNO3 is 1:1 so you also need 0.000375 moles of KOH to neutralise the nitric acid
Now you can work out the volume of KOH required:
Volume = Moles/Concentration = (0.000375)/0.05 = 0.0075 dm^3 = 7.5 cm^3
<span>Melting is an endothermic process (i.e. it absorbs heat), whereas freezing is an exothermic process (i.e. it releases heat, or can be thought of, albeit incorrectly from a thermodynamics standpoint, as "absorbing cold"). The standard enthalpy of fusion of water can be used for both scenarios, but standard enthalpy is in units of energy/mass, so 10 times as much energy will be absorbed in the former scenario (melting 10 kg of ice) than what will be absorbed in the latter scenario (freezing 1 kg of water). For both processes, assuming the water is pure and at standard atmospheric pressure, and the entire mass remains at thermal equilibrium, the temperature of both the solid and the liquid will remain at precisely 0 degrees Celsius (273 K) for the duration of the phase change.</span>
Answer:
Solid KOH will corrode the skin but a solution of KOH in triethyleneglycol will not.
The temperature is monitored with an external thermometer also because the sand looses some heat to energy exchange with the surrounding.
Explanation:
KOH is a deliquescent solid which is very corrosive upon contact with skin. Its solution in an organic liquid is not corrosive.
Secondly, when exposed to the surrounding, heat is lost according to the laws of thermodynamics.