2. Which is true of all elements?
1 answer:
You might be interested in
Answer:
24 hours
Explanation:
The computation is shown below:
The needed mole of is
= 5 ÷22.4 = n
Also 1 mole of required four electric charge
Now the charge needed is
= n × 4 × 96,500 C
= 4 × 96,500 × 5 c ÷ 22.4
= 86160.714 C
Now
q = i t
t = q ÷ i
= 86160.714 C ÷ 0.995
= 86593.7 seconds
= 24 hours
Hence, the correct option is A.
Answer:
²⁵ Mg = 10.00%
²⁶ Mg = 11.0%
Explanation:
Given that:
Magnesium ²⁴Mg has an abundance of 78.99%
Hence, (100 - 78.99)% = 21.01%
21.01% is the abundance of ²⁵ Mg and ²⁶ Mg
Suppose,
²⁵ Mg = x
²⁶ Mg = (21.01 - x)%
Then;
avg. atomic mass =
where the avg. atomic mass = 24.3050
∴
2430.5 = 2440.46915 -0.9968 x
0.9968x = 2440.46915 - 2430.5
0.9968x = 9.96915
x = 9.96915/0.9968
x = 10.00%
∴ Recall that:
²⁵ Mg = x
²⁶ Mg = (21.01 - x)%
²⁵ Mg = 10.00%
²⁶ Mg = (21.01 - 10.00)%
²⁶ Mg = 11.0%
Answer:
pH of the benzoic acid solution = 3.35
Explanation:
Benzoic acid is a weak monoprotic acid
pKa = 4.2
⇒ Ka = 6.3 x 10⁻⁵
C₆H₅COOH ⇄ C₆H₅COO⁻ + H⁺
Initial concentration C molar 0 0
At equilibrium (c - cα) cα cα
Acid dissociation constant Ka =
⇒ 6.3 x 10⁻⁵ = α²c ................(1)
(for weak electrolyte 1 -α = 1)
Concentration of benzoic acid C = 25 x 0.126 x 10⁻³ = 0.00315 molar
From eqn (1)
α² =
⇒ α = √( )
⇒ α = 0.14
So concentration of H⁺ ion = 0.14 x 0.00315 = 0.000441
pH = - log 0.000441 = 3.35
We not considered H⁺ concentration of water because pH < 7