Answer:Rubidium and Strontium
Explanation:
First, we need to get the value of Ka:
when Ka = Kw / Kb
we have Kb = 1.8 x 10^-5
and Kw = 3.99 x 10^-16 so, by substitution:
Ka = (3.99 x 10^-16) / (1.8 x 10^-5) = 2.2 x 10^-11
by using the ICE table :
NH4+ + H2O →NH3 + H+
intial 0.013 0 0
change -X +X +X
Equ (0.013-X) X X
when Ka = [NH3][H+] / [NH4+]
by substitution:
2.2 x 10^-11 = X^2 / (0.013 - X) by solving this equation for X
∴X = 5.35 x 10^-7
∴[H+] = X = 5.35 x 10^-7
∴PH = - ㏒[H+]
= -㏒(5.35 x 10^-7)
= 6.27
Answer:
E) 0.90
Explanation:
In TLC (Thin-Layer-Chromatography) retention factor RF is defined as the ratio between distance of the sample and the solvent front. RF is very important in chemistry to know the composition of any sample by comparison.
In the problem, as the sample has a distance of 0,20cm from the solvent front, the distance of the sample is:
2,0cm - 0,20 cm =<em> 1,8 cm</em>. Thus, RF is:
RF = 1,8cm / 2,0cm = 0,90
<em>E) 0,90</em>
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I hope it helps!
Answer:
Molecular Mass:
1. 40g per mole
2. 19g per mole
3. 64g per mole
4. 32 g per mole
5. 17g per mole
6. 59.5g per mole
7.58.5 g per mole
8.220g per mole
9. 78g per mole
10. 200g per mole
Explanation:
Molecular Mass = Number of atom x atomic mass of an element
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