At temperatures above 32°F (0°C), pure water ice melts and changes state from a solid to a liquid (water); 32°F (0°C) is the melting point. For most substances, the melting and freezing points are about the same temperature.
Hope i didn't give you to much info that all the info about ice melting.
Answer:
The pH at the midpoint in the titration of an acid with a base is
A) equal to the pK of the corresponding base.
B) equal to the pK of the corresponding acid.
C) equal to 14 minus the pK of the corresponding acid.
D) equal to 14 plus the pK of the corresponding base.
E) none of the above
Explanation:
When a weak acid is titrated with a strong base, then a buffer solution is formed.
pH of a buffer solution can be calculated by using the formula:
![pH=pKa+log\frac{[salt]}{[acid]}](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D)
Exactly at the mid point,
[conjugate base of the salt]=[acid]
So, log [salt]/[acid] =0
Hence, pH of the solution will be equal to pKa of the weak acid.
Answer is option B.
D. Smallest unit of an element
Answer:
Percent yield = 61.58%
Explanation:
C4H9OH + NaBr + H2SO4 --> C4H9Br + NaHSO4 + H2O
From the reaction;
1 mol of C4H9OH reacts with 1 mol of NaBr and 1 mol of H2SO4 to form 1 mol of C4H9Br
We have to obtain the limiting reagent. We do this by calculatig the mols of each reactant in the reaction;
Number of moles = Mass / Molar mass
C4H9OH; 15 / 74g/mol = 0.2027
NaBr; 22.4 / 102.89 = 0.2177
H2SO4; 32.7 / 98 = 0.3336
In this case, the limiting reagent is C4H9OH, it determines the amount of product formed.
From the stoichometry of the reaction; one mole of C4H9OH forms one mole of C4H9Br. This means 0.2027 mol of C4H9Br was formed.
Mass = Number of moles * Molar mass
Mass of C4H9Br formed = 0.2027 * 137
Mass = 27.77g
Percent yield = (Practical yield / theoretical yeield ) * 100%
Percent Yield = 17.1 / 27.77 * 100
Percent yield = 61.58%
