Answer:
% Mg = 16.2 % ≈ 16 %
%N = 18.9 % ≈ 19 %
% O = 64.9 % ≈ 65 %
Explanation:
Step 1: Data given
Molar mass Mg(NO3)2 = 148 g/mol
Molar mass Mg = 24 g/mol
Molar mass N = 14 g/mol
Molar mass O = 16 g/mol
Step 2: Calculate the percent composition
% Mg = (24/148) *100%
% Mg = 16.2 % ≈ 16 %
% N = (2*14 / 148) * 100%
%N = 18.9 % ≈ 19 %
% O = (6*16/148) * 100%
% O = 64.9 % ≈ 65 %
What helps me to balance equations is to list the elements i have on each side of the equation, and use tally marks to see what I have and don't have. Then when I'm done balancing, I tally again to make sure everything matches up.
On the left side, you have 1 Al, and 2 O. On the right side, 1 Al and 3 O.
In order for the equation to balance, you need to place a 2 in front of the AlO on the right side. This would make the Al have 2 atoms and the O have six. On the left side, you need to place a 2 in front of the Al and a 3 in front of the O, making it six. Left side: 2 Al's 6 O's. Right side: 2 Al's and 6 O's. Matches!
Answer:
Since pH can be affected by chemicals in the water, pH is an important indicator of water that is changing chemically
Explanation:
pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water. Water that has more free hydrogen ions is acidic, whereas water that has more free hydroxyl ions is basic
The quantum numbers for the last valence electron in nickel are (3, 2, 0, -½).
The electron configuration of nickel is [Ar]4s²3d⁸
The last electron added is a 3d electron, so <em>n</em> = 3 and <em>l</em> = 2.
We construct a table of quantum numbers.
<u>Element </u><em><u>n</u></em><u> </u><em><u>l</u></em><u> </u><em><u>m</u></em><u>ₗ mₛ </u>
Sc 3 2 2 +½
Ti 3 2 1 +½
V 3 2 0 +½
Cr 3 2 -1 +½
Mn 3 2 -2 +½
Fe 3 2 2 -½
Co 3 2 1 -½
Ni 3 2 0 -½
The quantum numbers for the last electron in nickel are (3, 2, 0, -½).
So use equation: ΔH = MCΔT
M = mass of water
C = waters specific heat capacity (4.18)
ΔT = the temp. change of the reaction
ΔH = 100 x 4.18 x 10 = 4180J or 41.8KJ
so the cube absorbed 4180J of energy
hope that helps
