Ionization Trend: First ionization energy will increase left to right across a period and increase bottom to top of a family (column).
A) Sr, Be, Mg are all in column 2 of the periodic table. Based on the first ionization rule above, from increasing to decreasing energy, the order is: Be, Mg, Sr
B) Bi, Cs, Ba are all in the same row of the periodic table. Based on the first ionization rule above, from increasing to decreasing energy, the order is: Bi, Ba, Cs
C) Same rule as above. Order is: Na, Al, S
<u>We are given:</u>
Mass of ice = 21 grams
The ice is already at 0°c, the temperature at which it melts to form water
Molar heat of fusion of Ice = 6.02 kJ/mol
<u>Finding the energy required:</u>
<u>Number of moles of Ice: </u>
Molar mass of water = 18 g/mol
Number of moles = given mass/ molar mass
Number of moles = 21 / 18 = 7/6 moles
<u>Energy required to melt the given amount of ice:</u>
Energy = number of moles * molar heat of fusion
Energy = (7/6) * (6.02)
Energy = 7.02 kJ OR 7020 joules
Answer:
53.6 g of N₂H₄
Explanation:
The begining is in the reaction:
N₂(g) + 2H₂(g) → N₂H₄(l)
We determine the moles of each reactant:
59.20 g / 28.01 g/mol = 2.11 moles of nitrogen
6.750 g / 2.016 g/mol = 3.35 moles of H₂
1 mol of N₂ react to 2 moles of H₂
Our 2.11 moles of N₂ may react to (2.11 . 2) /1 = 4.22 moles of H₂, but we only have 3.35 moles. The hydrogen is the limiting reactant.
2 moles of H₂ produce at 100 % yield, 1 mol of hydrazine
Then, 3.35 moles, may produce (3.35 . 1)/2 = 1.67 moles of N₂H₄
Let's convert the moles to mass:
1.67 mol . 32.05 g/mol = 53.6 g
<em>i think the answer is b </em>
Answer:
54.1 % Ca, 43.2 % O, 2.7% H
Explanation:
Molecular formula for calcium hydroxide is Ca(OH)₂
As we don't have a mass of Ca(OH)₂ to find out the percentage composition, we consider that the question refers to 1 mol of compound.
1 mol of hydroxide weighs 74.08 g
1 mol of hydroxide has 1 mol of Ca, therefore 40.08 g are Ca
2 moles of O therefore 32g are O
2 moles of H therefore 2 g are H
Percentage composition is known as (Mass of element/Total mass) . 100
(40.08 / 74.08) . 100 = 54.1 %
(32 / 74.08) . 100 = 43.2 %
(2 / 74.08) . 100 = 2.7%
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