International Business Machines Corp. said yesterday its second-quarter profit climbed 25 percent from a year earlier on a 19 percent gain in revenue.

Chemical New York Corp., the nation's sixth-largest bank-holding company, and General Electric Co. also reported improvement. But Eastern Airlines said it lost $94.4 million in the first half of this year.

IBM, the world's largest computer maker, attributed its better results to increased sales of both new and previously leased equipment, and to improved operating margins.

IBM said earnings rose to $1.34 billion ($2.22 a share), from $1.08 billion ($1.81) a year earlier. Revenue climbed to $9.59 billion from $8.05 billion.

For first-half 1983, IBM's profit climbed 24 percent to $2.32 billion ($3.84), from $1.87 billion ($3.14). Six-month revenue rose 18 percent to $17.9 billion from $15.1 billion.

Chemical New York Corp. reported a second-quarter profit of $69.7 million, a 21 percent increase from $57.6 million a year ago. Chairman Donald C. Platten said profit from interest income and fees offset loan losses and nonperforming loans involving several large U.S. and Latin American borrowers. Nonperforming loans are those on which interest or principal payments or both have been missed or delayed.

Chemical said its second-quarter net per share was $2.17, up from $2.05. It said its six-month net was $141.2 million ($4.62), up from $119.3 million ($4.46).

The parent of Chemical Bank said the second-quarter provision for loan losses--funds put aside should loans go bad--was $27.9 million, up from $24.7 million. Actual charge-offs were $26 million, up from $19.5 million. In the first half, the loan-loss provision was $56.6 million, up from $40.3 million a year ago. Charge-offs were $54.5 million, compared with $30.9 million.

As of June 30, assets were $48.9 billion, up from $48.3 billion.

General Electric Co. had 12 percent gains in earnings in both the second quarter and first half.

Earnings for the quarter were $521 million ($1.15) on revenues of $6.72 billion, up from $465 million ($1.03) on sales of $6.63 billion. The 1982 earnings were restated to reflect a two-for-one stock split in April.

First-half profit was $946 million ($2.08) on revenues of $12.82 billion, up from $842 million ($1.86) on revenues of $12.66 billion.

Eastern Airlines, continuing to lose record amounts of money because of discount fares and the threat of a strike, said it lost $33.7 million during the second quarter. That follows a record $60.7 million loss in the first three months. The losses are up from $54 million in the first six months of 1982. The per-share loss was $4.28, compared with $2.59 a year earlier.

In all of 1982, Eastern lost $74.9 million, following a loss of $65.9 million in 1981 and a $17.3 million loss in 1980.

"We're simply not generating enough traffic to compensate for the very, very low fares," said Eastern spokesman Jim Ashlock. "The second quarter has been rough on the whole industry."

In all of 1982, Eastern lost $74.9 million, following a loss of $65.9 million in 1981 and a $17.3 million loss in 1980. Thus, since 1980 and through June of this year, Eastern has lost $242.5 million.

Eastern Chairman Frank Borman predicted in April that Eastern would bounce back by the end of the year. Borman was not available for comment yesterday.

Also yesterday, Eastern filed with the Securities and Exchange Commission a registration statement saying it will make a stock offering later this month. The statement said 5 million units, each consisting of two shares of common stock, will be available. The value of the stock will be determined in the market.