Standard Oil of Indiana yesterday reported that its profits for the second quarter rose to $488.2 million ($1.68 a share) on sales of $7.3 billion, compared with net income of $350.2 million ($1.19) on sales of $4.6 billion for the 1979 second quarter.

For the 1980 first half, the company's earnings increased tok $1.06 billion from $700.2 million for the first half of 1979. Revenue for the six-month period was $13.7 billion, compared with $9 billion for the 1979 first half.

Chairman John E. Swearingen said more than half of the earnings increase was a result of foreign operations and reflected markedly higher worldwide prices for crude and refined products. He said prospects for the second half of 1980 are good but that he does not expect profits gains to equal the earnings growth of the first half.

The Du Pont Co. reported yesterday that preliminary earnings per share of common stock for the second quarter were down 25 percent at $1.19, compared with $1.59 for the second quarter of 1979. The earnings per share were 28 percent lower than the $1.66 recorded for this year's first quarter.

Net income for the second quarter was $176.6 million on sales of $3.41 billion, compared with $232.8 million on sales of $3.24 billion for the comparable quarter last year.

For the first six months of 1980, Du Pont had sales of $6.98 billion, up 11 percent from the $6.26 billion for the first half of 1979. Net income for the first half of 1980 was $421.0 million ($2.85 per share), compared with $481.2 million ($3.29) for the first half of 1979.

Du Pont Chairman Irving S. Shapiro said the U.S. recession was felt first by the automotive and housing industries and affected most of his company's product lins during the second quarter. He said Du Pont's prospects for the near term will depend largely on the performance of the economy generally but saw some optimistic signs in improved fuel efficiency in new models of U.S. cars, inventory levels and the recent drop in interst rates.

Monsanto second-quarter net income for 1980 was down substantially at $23.2 million (64 centss fully diluted), compared with $59.5 million ($1.63) for the second quarter of 1979. The company said that the closing of its European nylon operations reduced earnings per share by $1.18 during the 1980 second quarter.

Consolidated net sales for the second quarter were $1.55 billion, compared with 1979 second-quarter sales of $1.53 billion.

For the first half of 1980, net income was $187.4 million $5.31) on consolidated net sales of $3.37 billion, compared with income of $221.3 million ($6.03) on sales of $3.35 billion in the first half of 1979.

Second-quarter earnings for Trans World Corp. dropped from $58.8 million ($3.42 a share fully diluted) in 1979 to $11.9 million (41 cents) this year, but the company said 1979 second-quarter profits were distorted by United Airlines' strike which brought more passengers to TWA. Consolidated revenue for the quarter were $1.27 billion, compared with $1.14 for the 1979 second quarter.

For the first six months of 1980, Trans World reported a loss of $37.4 million (2.99) compared with a profit of $11.0 million (28 cents) for the first half of 1979.