The enthalpy change that accompanies a reaction is called the enthalpy of reaction (DHrxn). It is sometimes convenient to provide the value for DHrxn along with the balanced chemical equation for a reaction (also known as a thermochemical equation): 2H2(g) + O2(g) -> 2H2O(g) DH = -483.6 kJ.
It is the most recent in 9.7 inch iPad version. The display is also Retina with a huge resolution of 2048 x 536 pixels at 264 ppi. This new iPad retained the size 9.7 inches display size(250 mm) and also the LED back-lighting technology, plus fingerprint and scratch resistant coating. Random Access Memory is also the same: 1024 MB DDR II. The 4th generation iPad has the fastest processor, called Apple A6X. CPU features a 1.4 GHz dual core.
The iPad Air is Apple's fifth generation full-sized iPad tablet, and the name is definitelly fitting for this remarkable device. It is only 7.5 millimeters thin and weighs just 469 grams, making it the lightest slate of this size. Its screen is identical to the one we know from its predecessor - a 9.7-inch Retina Display with oleophobic coating and resolution of 1536 by 2048 pixels.