Exxon Mobil Corp
., the Irving-based energy giant, was the third most-generous corporation in American in 2011, according to a list of the Top 10 Corporate Donors compiled by The Chronicle of Philanthropy. Exxon gave $232,658,037 in cash and $2,007,943 in products, according to the Chronicle. It said that Exxon’s largest grant was $27 million to the National Math and Science Initiative in support of AP Training and Incentive and UTeach programs. Exxon told the Chronicle it expects to give the same amount in 2012.