Answer:
HC₂H₃O₂/KC₂H₃O₂
Explanation:
Considering the Henderson- Hasselbalch equation for the calculation of the pH of the basic buffer solution as:
![ pH=pK_b+log\frac{[salt]}{[acid]} ](https://tex.z-dn.net/?f=%0ApH%3DpK_b%2Blog%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D%0A)
For a best pair, the pKa value must be equal to pH.
NH₃/NH₄Cl forms a basic buffer and cannot account for pH = 5
out of the acidic buffer given,
So, HF , Ka = 3.5 × 10⁻⁴ , So pKa = 3.46
HC₂H₃O₂ , Ka = 1.8 × 10⁻⁵ , So pKa = 4.77
<u>The best pair to show pH = 5 is HC₂H₃O₂/KC₂H₃O₂</u>
Answer:
Reactions 1, 3 and 5
Explanation:
First thing's first, let's ensure that all the reactions given are balanced. This is given as;
CO(g) + 1/2 O2(g )→ CO2(g)
Li(s) + 1/2 F2(l) → LiF(s)
C(s) + O2(g) → CO2(g)
CaCO3(g) → CaO + CO2(g)
2Li(s) + F2(g) → 2LiF(s)
For the condition to be valid;
- There is by convention 1 mol of product made. This means we eliminate reactions with more than one mole of compound formed. This eliminates reaction 5.
- The lements haveto be in their state at room temperature. Fluorine is a gas, not a liquid, at room temperature ans pressure, so 2 is not a correct answer.
This leaves us with reactions 1, 3 and 5 as the correct reactions that satisify the condition.
Answer: 18
Justification:
1) The most common ion of calcium is Ca 2+
2) That means that the atom, neutral calcium, has lost two electrons.
3) The atomic number of calcium is 20.
4) Atomic number is the number of protons, so calcium has 20 protons.
5) Therefore, the neutral atom of calcium also has 20 electrons (to make a net charge of zero).
6) Then, the ion Ca 2+ has 20 - 2 = 18 electrons.
Answer: 18 electrons.
Answer:
Double replacement or double decomposition
Explanation:
In the reaction below, a double replacement or double decomposition has occurred.
2Na₃PO₄ + 3CaCl₂ → 6NaCl + Ca₃(PO₄)₂
This reaction occurs mainly between two ionic substances.
The reaction involves an actual exchange of partners to form new compounds. For example;
AB + CD → AD + CB
One of the following conditions below serves as the driving force for double replacement reactions:
- Formation of an insoluble compound or precipitate.
- Formation of water or any other non-ionizing compound
- Liberation of a gaseous product.
Answer:
=0.337mol Ca this is the correct answer :)
