Answer:
Final pH: 9.49.
Round to two decimal places as in the question: 9.5.
Explanation:
The conjugate of B is a cation that contains one more proton than B. The conjugate of B is an acid. As a result, B is a weak base.
What's the pKb of base B?
Consider the Henderson-Hasselbalch equation for buffers of a weak base and its conjugate acid ion.
![\displaystyle \text{pOH} = \text{pK}_b + \log{\frac{[\text{Salt}]}{[\text{Base}]}}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Ctext%7BpOH%7D%20%3D%20%5Ctext%7BpK%7D_b%20%2B%20%5Clog%7B%5Cfrac%7B%5B%5Ctext%7BSalt%7D%5D%7D%7B%5B%5Ctext%7BBase%7D%5D%7D%7D)
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![\displaystyle \text{pK}_b = \text{pOH} -\log{\frac{[\text{Salt}]}{[\text{Base}]}}\\\phantom{\text{pK}_b} = 4.5 - \log{\frac{0.750}{1.05}} \\\phantom{\text{pK}_b} =4.64613](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Ctext%7BpK%7D_b%20%3D%20%5Ctext%7BpOH%7D%20-%5Clog%7B%5Cfrac%7B%5B%5Ctext%7BSalt%7D%5D%7D%7B%5B%5Ctext%7BBase%7D%5D%7D%7D%5C%5C%5Cphantom%7B%5Ctext%7BpK%7D_b%7D%20%3D%204.5%20-%20%5Clog%7B%5Cfrac%7B0.750%7D%7B1.05%7D%7D%20%5C%5C%5Cphantom%7B%5Ctext%7BpK%7D_b%7D%20%3D4.64613)
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What's the new salt-to-base ratio?
The 0.005 mol of HCl will convert 0.005 mol of base B to its conjugate acid ion BH⁺.
Initial:
;
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After adding the HCl:
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Assume that the volume is still 0.5 L:
![\displaystyle [\text{B}] = \frac{n}{V} = \frac{0.520}{0.5} = 1.04\;\text{mol}\cdot\text{dm}^{-3}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5B%5Ctext%7BB%7D%5D%20%3D%20%5Cfrac%7Bn%7D%7BV%7D%20%3D%20%5Cfrac%7B0.520%7D%7B0.5%7D%20%3D%201.04%5C%3B%5Ctext%7Bmol%7D%5Ccdot%5Ctext%7Bdm%7D%5E%7B-3%7D)
.![\displaystyle [\text{BH}^{+}] = \frac{n}{V} = \frac{0.380}{0.5} = 0.760\;\text{mol}\cdot\text{dm}^{-3}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5B%5Ctext%7BBH%7D%5E%7B%2B%7D%5D%20%3D%20%5Cfrac%7Bn%7D%7BV%7D%20%3D%20%5Cfrac%7B0.380%7D%7B0.5%7D%20%3D%200.760%5C%3B%5Ctext%7Bmol%7D%5Ccdot%5Ctext%7Bdm%7D%5E%7B-3%7D)
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What's will be the pH of the solution?
Apply the Henderson-Hasselbalch equation again:
![\displaystyle \text{pOH} = \text{pK}_b + \log{\frac{[\text{Salt}]}{[\text{Base}]}} = 4.64613 + \log{\frac{0.760}{1.04}} = 4.50991](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Ctext%7BpOH%7D%20%3D%20%5Ctext%7BpK%7D_b%20%2B%20%5Clog%7B%5Cfrac%7B%5B%5Ctext%7BSalt%7D%5D%7D%7B%5B%5Ctext%7BBase%7D%5D%7D%7D%20%3D%204.64613%20%2B%20%5Clog%7B%5Cfrac%7B0.760%7D%7B1.04%7D%7D%20%3D%204.50991)
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The final pH is slightly smaller than the initial pH. That's expected due to the hydrochloric acid. However, the change is small due to the nature of buffer solutions: adding a small amount of acid or base won't significantly impact the pH of the solution.
Atomic mass Na = 22.99 u.m.a
22.99 g ------------------ 6.02x10²³ atoms
175 g -------------------- ?? atoms
175 x (6.02x10²³) / 22.99 => 4.58x10²⁴ atoms
hope this helps!
Answer:
Option d is correct = Negative ion
Explanation:
We know that an atom consist of electrons, protons and neutrons. Neutrons and protons are present inside the nucleus while electrons are present out side the nucleus. Electron has a negative charge and is written as e⁻. The mass of electron is 9.10938356×10⁻³¹ Kg
. While mass of proton and neutron is 1.672623×10⁻²⁷Kg and 1.674929×10⁻²⁷ Kg respectively.
Symbol of proton= P⁺
Symbol of neutron= n⁰
The number of electron or number of protons are called atomic number while mass number of an atom is sum of protons and neutrons. The umber of protons and electrons are always equal to make the atom electrically neutral and when an atom loses its valance electron the number of protons increases and thus positive charge increased and atom form cation.
When an atom gain electron negative charge increase because of more number of electron thus atom form negative ion or anion. For example,
Anion formation:
X + e⁻ → X⁻
Cation formation:
X → X⁺ + e⁻
Thus option d is correct option.
Answer:
The state of matter of rain is liquid. Clouds are 2 states of matter, liquid and gas
Explanation:
