Answer:
The question 7 answer is false
the question 8 answer is true
The number of mole of HCl needed for the solution is 1.035×10¯³ mole
<h3>How to determine the pKa</h3>
We'll begin by calculating the pKa of the solution. This can be obtained as follow:
- Equilibrium constant (Ka) = 2.3×10¯⁵
- pKa =?
pKa = –Log Ka
pKa = –Log 2.3×10¯⁵
pKa = 4.64
<h3>How to determine the molarity of HCl </h3>
- pKa = 4.64
- pH = 6.5
- Molarity of salt [NaZ] = 0.5 M
- Molarity of HCl [HCl] =?
pH = pKa + Log[salt]/[acid]
6.5 = 4.64 + Log[0.5]/[HCl]
Collect like terms
6.5 – 4.64 = Log[0.5]/[HCl]
1.86 = Log[0.5]/[HCl]
Take the anti-log
0.5 / [HCl] = anti-log 1.86
0.5 / [HCl] = 72.44
Cross multiply
0.5 = [HCl] × 72.44
Divide both side by 72.44
[HCl] = 0.5 / 72.4
[HCl] = 0.0069 M
<h3>How to determine the mole of HCl </h3>
- Molarity of HCl = 0.0069 M
- Volume = 150 mL = 150 / 1000 = 0.15 L
Mole = Molarity x Volume
Mole of HCl = 0.0069 × 0.15
Mole of HCl = 1.035×10¯³ mole
<h3>Complete question</h3>
How many moles of HCl need to be added to 150.0 mL of 0.50 M NaZ to have a solution with a pH of 6.50? (Ka of HZ is 2.3 x 10 -5 .) Assume negligible volume of the HCl
Learn more about pH of buffer:
brainly.com/question/21881762
<span>An atom's identity, that is, whether it is 'oxygen' or 'plutonium', for example, is determined solely by the number of protons in the nucleus. The number of neutrons also plays a part - a differing number of neutrons can change an atom from one isotope of an element into another, but the atoms would still remain the same element, albeit a different isotope. The number of electrons orbiting the atom does not change the identity of the atom, only it's electronic state. Take electrons away and it becomes a positively charged ion of the same element. Add electrons and it becomes a negatively charged ion, but still of the same element.</span>
The question is incomplete, the complete question is;
A 31 g sample of a compound that contains only the elements C,H and N is completely burned in O2 to produce 44.0 g of CO2, 45.0 g of H2O, and 92.0 g of NO2. Determine the empirical formula of the compound.
Answer:
CH5N2
Explanation:.
Mass of C = 44.0g/44.0 g/mol = 1 mol * 1 = 1 mole of C
Mass of H = 45.0 g/18 g/mol = 2.5 moles * 2 = 5 moles of H
Mass of N = 92.0 g/46 g/mol = 2 moles * 1 = 2 moles of N
Dividing through by the lowest mole ratio;
1/1, 5/1, 2/1
1 : 5 : 2
Hence the empirical formula is;
CH5N2
