Nitrogen monoxide, NO, can be oxidised to form nitrogen dioxide, NO2: 2NO + O2 → 2NO2 What is the oxidising agent in this reaction? A Nitrogen B Nitrogen dioxide C Nitrogen monoxide D Oxygen Your answer - OCR Gateway - GCSE Chemistry - Question 14 - 2023 - Paper 1

To determine the oxidising agent in this reaction, we need to understand what oxidation and reduction mean. An oxidising agent is a substance that gains electrons and, in the process, causes another substance to be oxidised.

In the given reaction:

$2NO + O_2 \rightarrow 2NO_2$

we can observe that nitrogen monoxide (NO) reacts with oxygen (O2) to form nitrogen dioxide (NO2). Here, oxygen is the species that gets reduced, meaning it gains electrons, while nitrogen monoxide is oxidised as it loses electrons to form nitrogen dioxide.

Thus, the oxidising agent in this reaction is oxygen, making the answer:

D. Oxygen