Why did tensions develop between great britain and china in the mid-19th century?

There was a lot of tension between Great Britain and China due to the opium trade of British merchants and the Chinese of the Qing dynasty. Since the British needed Chinese goods but did not have enough silver for trading, they decided to exchange Chinese goods for opium instead. Because of the opium trade, there were many Chinese who became addicted to the substance. This lead to a high number of unstable individuals in China. This lead to the Chinese revolting against the British merchants. This, in turn, lead to the opium war.