Physical change
iron nail have high melting point, thus, when it is heated, it will not melt very easily.
chemical change
iron nail can rust due to the exposure to the air(oxygen). iron in the nail and oxygen in the air will react together to form iron oxide(rust).
furthermore, the reaction is irreversible.
The grade of coal increases with compaction.
<h3>What is Compaction?</h3>
When something is crushed or compressed, it becomes compacted. After being collected, trash is often compressed to make it smaller and take up less room. Compaction is the process of making anything more compact, dense, or firmly packed.
grade of coal - The highest grade of coal is anthracite. It is a black, glossy, hard, brittle coal that is frequently referred to as hard coal. It has a high proportion of fixed carbon and a low proportion of volatile matter. Between subbituminous and anthracite, bituminous coal is the intermediate rank of coal.
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The question is incomplete, the complete question is:
A chemist measures the amount of iodine solid produced during an experiment. He finds that 8.31 g of iodine solid is produced. Calculate the number of moles of iodine solid produced. Round your answer to the correct number of significant digits.
<u>Answer: </u>The number of moles of solid iodine produced is 0.0327 moles
<u>Explanation:</u>
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
......(1)
Given mass of solid iodine = 8.31 g
Molar mass of solid iodine = 253.8089 g/mol
Plugging values in equation 1:
Hence, the number of moles of solid iodine produced is 0.0327 moles
Answer:
40.5 g of P₄O₁₀ are produced
Explanation:
We state the reaction:
P₄ + 5O₂ → P₄O₁₀
We do not have data from P₄ so we assume, it's the excess reactant.
We need to determine mass of oxygen and we only have volumne so we need to apply density.
Density = mass / volume, so Mass = density . volume
Denstiy of oxygen at STP is: 1.429 g/L
1.429 g/L . 16.2L = 23.15 g
We determine the moles: 23.15 g . 1mol / 33.472g = 0.692 moles
5 moles of O₂ can produce 1 mol of P₄O₁₀
Our 0.692 moles may produce (0.692 . 1)/ 5 = 0.138 moles
We determine the mass of product:
0.138 mol . 292.88 g/mol = 40.5 g
