A rigid tank of volume 70 ft3, initially contains air at 14.7 lbf/in.2, 520oR. The tank is connected by a valve to a much larger tank containing air at 90 lbf/in.2, 520oR. The valve is opened and air flows slowly until the smaller tank achieves a pressure of 90 lbf/in.2and a temperature of 630oR. The air can be modeled as an ideal gas, and kinetic and potential energy effects can be neglected. For the contents of the smaller tank as the control volume, determine the heat transfer, in Btu. TABLE A-20E Ideal Gas Specific Heats of Som lemp. Air 40 0.240 0.171 1.401 100 0.240 0.172 1.400 200 0.2410.173 1.397 300 0.2430.1741.394 400 o.245o.1761.389 500 o.248 o.1791.383 600 o.250 o.182 1.377 700 o.254 0.185 1.371 800 0.257 0.188 1.365 900 o.2590.1911.358 1000 o.263 0.1951.353 1500 o.276o.2081.330 2000o.286o.2171.312