A reaction in which heat is evolved is an exothermic reaction while a reaction in which heat is absorbed is an endothermic reaction.
In the first case; Na2CO3 + H2SO4, we can see that this is an acid - base reaction therefore it is a neutralization reaction. Since the tube was hot after reaction, heat is given off so it is exothermic.
In the second case; NaOH + H2SO4, we can see that this is an acid - base reaction therefore it is a neutralization reaction. We are told that the tube is not hot but we don't know the initial temperature of the tube or if it was colder than it's initial temperature so we can not make any inference regarding whether the reaction is endothermic or exothermic.
Lastly, the reaction, NaCl + HC2H5OH does not occur so we mark "no reaction". We are told that the tube is not hot but we don't know the initial temperature of the tube or if it was colder than it's initial temperature so we can not make any inference regarding whether the reaction is endothermic or exothermic.
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Actually the correct answer must be:
The limiting reactant in the reaction is the one which has
the lowest ratio of moles available
over coefficient in the balanced equation
This is because the actual mass or number of moles of the
reactant does not directly dictate if it is a limiting reactant, this must be
relative to the other reactants.
So the answer is:
e. none of the above
Mole = Mass / Molar mass
6.12 moles = Mass / 74.92 g/mol
Mass = 6.12 moles x 74.92 g/mol
Mass = 458.51g
Well you know that you have to balance out the equation to 0. So if I is -1 and Ca is +2 you know that I had to equal to -2. So you can do that by having two of them. So Ca=+2 and I2=-2 so CaI2 would equal 0 meaning that would be the correct answer. Hope that I explained that correct :)
I’m not sure it’s correct but I think it’s D) He used voltage adjustments to make charges oil drops float
