Asample of oxygen gas (o2) has a volume of 7.51 l at a temperature of 19°c and a pressure of 1.38 atm. calculate the moles of o2 molecules present in this gas sample. a. 0.217 mol b. 0.866 mol c. 6.65 mol d. 0.433 mol =n

The moles of O₂ which are present in the sample are 0.433. (option D)

Explanation:

We should apply the Ideal Gases Law, to solve this:

P . V = n. R. T

1.38 atm . 7.51L = n . 0.082 . 292K

(1.38 atm . 7.51L) / (0.082 . 292K) = n

0.433 moles = n

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.