Answer:
The pH changes by 2.0 if the [A-]/[HA] ratio of a base/weak acid mixture changes from 10/1 to 1/10.
Explanation:
To solve this problem we use the<em> Henderson-Hasselbach equation</em>:
Let's say we have a weak acid whose pKa is 7.0:
If the [A⁻]/[HA] ratio is 10/1, we're left with:
Now if the ratio is 1/10:
The difference in pH from one case to the other is (8.0-6.0) 2.0.
<em>So the pH changes by 2.0</em> if the [A-]/[HA] ratio of a base/weak acid mixture changes from 10/1 to 1/10.
<u>Keep in mind that no matter the value of pKa, the answer to this question will be the same.</u>
The balanced equation for the above reaction is as follows;
CaCO₃ + 2HCl ----> CaCl₂ + H₂O + CO₂
stoichiometry of CaCO₃ to HCl is 1:2
molar volume states that 1 mol of any gas occupies a volume of 22.4 L at STP.
volume of 22.4 L occupied by 1 mol
therefore 0.56 L occupied by - 0.56 L / 22.4 L/mol = 0.025 mol
number of HCl moles reacted - 0.025 mol
2 mol of HCl reacts with 1 mol of CaCO₃
therefore 0.025 mol reacts with - 0.025/2 = 0.0125 mol
mass of CaCO₃ required - 0.0125 mol x 100 g/mol = 1.25 g
1.25 g of CaCO₃ is required
Given :
A chemical compound
.
To Find :
Fix the formula for
and write the full correct formula.
Solution :
We know, Potassium( K ) and Fluorine( F ) both have a valency of 1 i.e potassium can donate one electron and Fluorine can accept one electron only.
So, the chemical formula
is wrong because no element has filled electron.
Therefore, to stabilise the molecule, 1 Potassium atom should make a bond from 1 Fluorine i.e KF ( correct formula ) .
Hence, this is the required solution.
Answer:
If a substance undergoes a physical change, then it will retain most of its original properties because no new substance is formed.
If a substance undergoes a chemical change, then it will not retain its original properties because a new substance is formed.
Explanation:
So in shorter words its options 2 and 3