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

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.