The percet of Al will be 100 times the mass of Al in the formula divided by the molar mass of the compound.
This table shows all the calculations involved
Compound: Al2 (OH)5 Cl
element # of atomic mass in the %
atoms mass formula
g/mol
Al 2 27 2*27 = 54 g (54 / 174.5)*100 = 30.9%
O 5 16 5*16 = 80 g
H 5 1 5*1 = 5 g
Cl 1 35.5 1*35.5 = 35.5 g
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molar mass 174.5 g
Answer: 30.9%
NiCl₂ commonly forms a green aqueous solution.
The granite block transferred <u>4080 J</u> of energy, and the mass of the water is <u>35.8 g</u>.
1. <em>Energy from granite block
</em>
The formula for the heat (<em>q</em>) transferred is
<em>q = mC</em>Δ<em>T</em>
<em>m</em> = 126.1 g; <em>C</em> = 0.795 J·°C⁻¹g⁻¹; Δ<em>T</em> = <em>T</em>_f – <em>T</em>_i = 51.9 °C - 92.6 °C = -40.7 °C
∴ <em>q</em> = 126.1 g × 0.795 J·°C⁻¹g⁻¹ × (-40.7 °C) = -4080 J
The granite block transferred 4080 J.
2. <em>Mass of water
</em>
<em>q = mC</em>Δ<em>T
</em>
<em>m = q</em>/(<em>C</em>Δ<em>T</em>)
<em>q </em>= 4080 J; <em>C</em> = 4.186 J·°C⁻¹g⁻¹; Δ<em>T</em> = <em>T</em>_f – <em>T</em>_i = 51.9 °C – 24.7 °C = 27.2 °C
∴ <em>m</em> = 4080 J/(4.186 J·°C⁻¹g⁻¹ × 27.2 °C) = 35.8 g
The mass of the water is 35.8 g.
When we can get the Kinetic energy from this formula KE= 1/2 M V^2
and we can get the potential energy from this formula PE = M g H
we can set that the kinetic energy at the bottom of the fall equals the potential energy at the top so,
KE = PE
1/2 MV^2 = M g H
1/2 V^2 = g H
when V is the velocity, g is an acceleration of gravitational force and H is the height of the fall.
∴ v^2 = 2 * 9.8 * 8 = 156.8
∴ v= √156.8 = 12.5 m/s