Answer:
B and C
Explanation:
When we have to do a buffer solution we always have to choose the reaction that has the <u>pKa closer to the desired pH value</u>. When we find the pKa values we will obtain:
![pKa_1=-Log[6.9x10^-^3]=2.16](https://tex.z-dn.net/?f=pKa_1%3D-Log%5B6.9x10%5E-%5E3%5D%3D2.16)
![pKa_2=-Log[6.2x10^-^8]=7.20](https://tex.z-dn.net/?f=pKa_2%3D-Log%5B6.2x10%5E-%5E8%5D%3D7.20)
![pKa_3=-Log[4.8x10^-^13]=12.31](https://tex.z-dn.net/?f=pKa_3%3D-Log%5B4.8x10%5E-%5E13%5D%3D12.31)
The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which
is the <u>acid</u> and
is the <u>base</u>. Therefore the answer for the first question is B and the answer for the second question is C.
Answer:
Explanation:
4NH₃ (g) + 3O₂ (g) ⇒ 2N₂ (g) + 6H₂ O(1)
Δ
ΔH r =(2ΔH f(N 2 )+6ΔH f (H 2 O(l)))−(4ΔH f (NH 3 (g))+3ΔH f (O 2 (g)))
ΔH rex =[2×0+6×(−286)]−[4×(−46)+3×0]=−1716+186
ΔH rex =−1532kJ/mol
Thermodynamics is a branch of physical chemistry that studies heat and its effects and interactions. Governed by the four main laws, thermodynamics plays a huge role in physics and chemistry, and is also responsible for the law of conservation of energy, a fundamental rule in science.
The atomic mass of Europium is 152 amu
Work:
151(0.4803) = 72.52 amu
153(0.5197) = 79.5 amu
72.5 + 79.5 = 152 amu
Data:
Arsenic Molar Mass = 74,9216 ≈ 75 u (<span>atomic mass unit)</span>
Solving:
1 mole of arsenic → 75g ------------ 6,02*10²³ molecules
..................................X -------------- 1 molecule
6,02*10²³X = 75
