An unknown substance is made only of identical atoms that cannot be broken down. This substance is a ________.
2 answers:
Answer: Element
Explanation:
Element is a pure substance which is composed of identical atoms. It can not be decomposed into simpler constituents using chemical reactions.Example: Silver
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: carbon dioxide
Thus an unknown substance is made only of identical atoms that cannot be broken down is an element.
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Explanation:
For the first part,
Reaction equation:
N₂ + 3H₂ → 2NH₃
Given:
Number of moles of NH₃ = 6 moles
Unknown:
Number of moles of N₂ = ?
Solution:
N₂ + 3H₂ → 2NH₃;
From the reaction above, we solve from the known specie to the unknown. Ensure that the equation is balanced;
2 moles of NH₃ is produced from 1 mole of N₂
6 moles of NH₃ will be produced from mole of N₂
= 3moles of N₂
The number of moles of N₂ is 3 moles
ii.
Given parameters:
Number of moles of sulfur = 2.4moles
Molar mass of sulfur = 32.07g/mol
Unknown:
Mass of sulfur = ?
Solution:
The number of moles of any substance can be found using the expression below;
Number of moles =
Mass of sulfur = number of moles of sulfur x molar mass
Insert the parameters and solve;
Mass of sulfur = 2.4 x 32.07 = 76.97g
<u>Answer:</u> The concentration of solution is 0.342 M
<u>Explanation:</u>
To calculate the molarity of solution, we use the equation:
We are given:
Mass of solute (Sodium chloride) = 15 g
Molar mass of sodium chloride = 58.5 g/mol
Volume of solution = 750 mL
Putting values in above equation, we get:
Hence, the concentration of solution is 0.342 M