<span>PbO
Let's look at each of the 4 compounds and see what's needed.
PbO.
* Oxygen has a valance shell that's missing 2 electrons and wants to get those 2 elections. Lead donates them, so you have a Lead (II) ions. This is a correct choice.
PbCl4
* Chlorine wants to grab 1 electron to fill it's valance shell and Lead donates that election. However, there's 4 chlorine atoms and every one of them wants and electron, and lead is donating all 4 of the desired electrons making the Lead (IV) ion. So this is a bad choice.
Pb2O
* Oxygen still wants 2 electrons and gets them from the lead. But there's 2 lead atoms and each of them donates 1 election making for 2 Lead(I) ions. So this too is a bad choice.
Pb2S
* Sulfur is in the same column of the periodic table as oxygen and if this compound were to exist would have similar properties as Pb2O and would have Lead(I) ions. So this is a bad choice.</span>
<u>Ans: Acetic acid = 90.3 mM and Sodium acetate = 160 mM</u>
Given:
Acetic Acid/Sodium Acetate buffer of pH = 5.0
Let HA = acetic acid
A- = sodium acetate
Total concentration [HA] + [A-] = 250 mM ------(1)
pKa(acetic acid) = 4.75
Based on Henderson-Hasselbalch equation
pH = pKa + log[A-]/[HA]
[A-]/[HA] = 10^(pH-pKa) = 10^(5-4.75) = 10^0.25 = 1.77
[A-] = 1.77[HA] -----(2)
From (1) and (2)
[HA] + 1.77[HA] = 250 mM
[HA] = 250/2.77 = 90.25 mM
[A-] = 1.77(90.25) = 159.74 mM
Answer:
The electrons that participate in chemical bonds are the valence electrons, which are the electrons found in an atom 's outermost shell.
Explanation:
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The volume of hydrogen gas that evolved is calculated as follows
by use of ideal gas equation
that is PV = nRT
P=745 mm hg
V= ?
R(gas constant)= 62.36 L.mm hg/mol.k
T= 20 + 273 = 293 k
n=number of moles which is calculated as follows
find the moles of Na used
= 0.52/23=0.023 moles
write the reacting equation
2Na +2H2O =2NaOH +H2
by use of reacting ratio between Na : H2 which is 2:1 therefore the mole of H2 = 0.023/2 =0.0115 moles
by making the volume the subject of the formula
v=nRT/P
V= (0.0115 x 62.36 x 293) / 745 = 0.283 L
