Answer:
73.2g
Explanation:
The reaction expression is given as:
P₄ + 6Cl₂ → 4PCl₃
Given parameters:
Volume of chlorine gas = 79.2L
Unknown:
Mass of Phosphorus needed = ?
Solution:
To solve this problem, let us find the number of moles of the chlorine gas.
Since the condition of the reaction is at STP;
22.4L of gas is contained in 1 mole
79.2L of chlorine gas will contain 
= 3.54mole
From the reaction expression;
6 moles of chlorine gas will react with 1 mole of P₄
3.54 mole of chlorine gas will completely react with 
= 0.59mole of P₄
Mass of P₄ = number of moles x molar mass
Molar mass of P₄ = 4 x 31 = 124g/mol
Mass of P₄ = 0.59 x 124 = 73.2g
The structure of proteins is ultimately determined by the sequence of nucleic acids.
The chemical formula for this compound : Cu₂SO₄-Copper(I) sulfate
<h3>Further explanation</h3>
Given
2 atoms of Copper, 1 atom of Sulfur and 4 atoms of Oxygen.
Required
The chemical formula
Solution
The number of atoms forming a compound is usually indicated from the subscript in the formula
From the problem it can be seen that the compound has:
2 atoms of Cu, 1 atom of S, and 4 atoms of O
So the formula:
<em>Cu₂SO₄</em>
The efficiency : 95%
<h3>Further explanation</h3>
Efficiency : the ratio between output and input work
In general, the value of the output of a machine is less than the value of the input because of the frictional force in the machine.
The greater the efficiency of the engine, the better the machine
Can be formulated :
w output = 190 J
W input = 200 J
The efficiency :
