Answer: During a phase change, such as melting or boiling, the kinetic energy increases.
Explanation:
Kinetic energy is the energy obtained by the molecules of a substance due to their motion.
When phase change such as melting or boiling takes place then it means heat is absorbed by the substance. As a result, their molecules more even more rapidly from one place to another due to which more number of collisions take place.
Hence, a change in phase of substance occurs as kinetic energy increases in melting or boiling process.
Thus, we can conclude that during a phase change, such as melting or boiling, the kinetic energy increases.
Answer:
37 mmol of acetate need to add to this solution.
Explanation:
Acetic acid is an weak acid. According to Henderson-Hasselbalch equation for a buffer consist of weak acid (acetic acid) and its conjugate base (acetate)-
![pH=pK_{a}(acetic acid)+log[\frac{mmol of CH_{3}COO^{-}}{mmol of CH_{3}COOH }]](https://tex.z-dn.net/?f=pH%3DpK_%7Ba%7D%28acetic%20acid%29%2Blog%5B%5Cfrac%7Bmmol%20of%20CH_%7B3%7DCOO%5E%7B-%7D%7D%7Bmmol%20of%20CH_%7B3%7DCOOH%20%7D%5D)
Here pH is 5.31, 
(acetic acid) is 4.74 and number of mmol of acetic acid is 10 mmol.
Plug in all the values in the above equation:
![5.31=4.74+log[\frac{mmol of CH_{3}COO^{-}}{10}]](https://tex.z-dn.net/?f=5.31%3D4.74%2Blog%5B%5Cfrac%7Bmmol%20of%20CH_%7B3%7DCOO%5E%7B-%7D%7D%7B10%7D%5D)
or, mmol of 
= 37
So 37 mmol of acetate need to add to this solution.
Answer:
pH of buffer =4.75
Explanation:
The pH of buffer solution is calculated using Henderson Hassalbalch's equation:
![pH=pKa+log[\frac{[salt]}{[acid]}](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%5B%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D)
Given:
pKa = 3.75
concentration of acid = concentration of formic acid = 1 M
concentration of salt = concentration of sodium formate = 10 M
![pH=3.75+log[\frac{10}{1}]=3.75+1=4.75](https://tex.z-dn.net/?f=pH%3D3.75%2Blog%5B%5Cfrac%7B10%7D%7B1%7D%5D%3D3.75%2B1%3D4.75)
pH of buffer =4.75
Answer: Option (A) is the correct answer.
Explanation:
Condensation is defined as the process in which vapors or gaseous phase changes into liquid phase.
Freezing is the process in which liquid phase changes into solid phase.
Evaporation is the process in which liquid phase changes into vapors or gaseous phase.
Melting is the process in which solid phase changes into liquid phase.
Therefore, we can conclude that names for given phase changes A and B is that A is condensation and B is freezing.
Answer: There are 
atoms present in 0.500 mol of 
.
Explanation:
According to the mole concept, there are 
atoms present in 1 mole of a substance.
In a molecule of there is only one carbon atom present. Therefore, number of carbon atoms present in 0.500 mol of are as follows.
Thus, we can conclude that there are atoms present in 0.500 mol of .
