The earnings season is in full swing with a large swath of companies on the S&P 500 index reporting their quarterly numbers this week. The general earnings picture is somber as Q1 earnings are expected to take a dip despite a flurry of positive surprises so far.Per our latest Earnings Trend report, total Q1 earnings are expected to skid 9.4% year over year on 0.8% lower revenues, factoring in the actual results from the 132 S&P 500 members that have reported till last Friday. This, if eventually happens, will mark the 4th straight quarter of earnings declines for the benchmark index.In this write-up, we put a spotlight on four chemical companies that are schedule to report this Thursday and Friday. The chemical industry falls under the broader Basic Materials sector which is among the sectors that have experienced double-digit earnings declines in first-quarter 2016 based on the earnings scorecard as of Apr 22. Earnings for the sector participants in the S&P 500 index are down -21.8% from the same period last year on -12.3% lower revenues.How the Chemical Industry Faring?The chemical industry is clawing its way back after being shaken by the global economic crisis. Despite being hobbled by a spate of challenges including headwinds from a strong greenback and a slowdown in emerging markets, the industry fared reasonably well last year on the back of strong momentum in the automotive market and a recovery in the construction space.The industry’s recovery momentum is expected to continue in 2016, aided by strength in the light vehicles market, an upswing in the housing sector and significant shale-linked capital investment. Chemical makers should also benefit from strategic measures including expansion into high-growth markets, cost management and productivity improvement actions as well as acquisitions. However, the industry faces certain roadblocks including a still weak agriculture market, soft demand in the energy space, lumpiness in Europe and a cooling Chinese economy.Chemical Stocks in Focus:While some big chemical names including DuPont DD and PPG Industries PPG have already reported their results, a number of major players in the space are scheduled to report this week.We take a sneak peek at four prominent chemical names that are gearing up to report their results this week – the busiest of this earnings season. The Dow Chemical Company DOW, which will report ahead of the opening gong on Thursday, is expected to continue its winning streak with another positive earnings surprise backed by its Zacks Rank #2 (Buy) and Earnings ESP of +1.21%. The U.S. chemical kingpin has an impressive surprise history, having beaten the Zacks Consensus Estimate in the trailing 4 quarters with an average beat of 18.37%.Dow remains committed to its portfolio management actions and operational execution amid a still difficult operating backdrop. While currency and challenges in agriculture market remain as headwinds, the company’s productivity improvement, cost control and growth actions as well as sustained strong momentum in its performance plastics business is expected to drive earnings in the to-be-reported quarter. (Read more: Dow Chemical Q1 Preview: Another Earnings Beat Coming?) Air Products and Chemicals, Inc. APD, which will report its fiscal second-quarter numbers ahead of the bell on Apr 28, is expected to come up with a positive earnings surprise as it sports a Zacks Rank #2 and Earnings ESP of +0.56%. The company has outperformed the Zacks Consensus Estimate in the trailing four quarters with an average beat of 2.73%.While currency headwind is expected to play spoilsport, the company’s aggressive cost-control measures, synergies from acquisitions, new business wins, and sustained pricing power should support its earnings in the to-be-reported quarter. (Read more: Air Products Q2 Earnings: A Beat in the Cards?) Eastman Chemical Co. EMN, which will report after the bell on Apr 28, faces a number of challenges this year including a sluggish global economy, lower crude oil prices and weakening currencies across Asia and Europe. While the company should gain from synergies of acquisitions, cost-cutting actions and continued momentum in its specialty businesses, continued pricing pressure across most of its businesses and currency headwinds are expected to dent its results in the to-be-reported quarter. (Read more: Eastman Chemical: Will FX, Weak Price Hit Q1 Earnings?)Eastman Chemical, which sports a Zacks Rank #4 (Sell), has an Earnings ESP of -1.96% for the first quarter. However, the company has beaten the Zacks Consensus Estimate in all the trailing 4 quarters with an average beat of 7.41%.Praxair Inc. PX, which will report its first-quarter results before the bell on Apr 29, is expected to gain from increasing application of industrial gases, especially hydrogen in the refining industry, oxygen in healthcare, and nitrogen and carbon dioxide in oil and gas industry. The company is expected to post a positive earnings surprise backed by its Zacks Rank #2 and Earnings ESP of +0.79%. (Read more: Praxair Q1 Earnings: Can It Beat on Solid Fundamentals?)Praxair has delivered better-than-expected results in 1 of the trailing 4 quarters, while reporting in-line results in the rest. Average earnings surprise for the stock stands at a positive 0.35%.Stay tuned! Check back later for our earnings coverage of these stocks.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report PPG INDS INC (PPG): Free Stock Analysis Report DU PONT (EI) DE (DD): Free Stock Analysis Report DOW CHEMICAL (DOW): Free Stock Analysis Report EASTMAN CHEM CO (EMN): Free Stock Analysis Report PRAXAIR INC (PX): Free Stock Analysis Report AIR PRODS & CHE (APD): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research