A student needs to prepare 500.0 ml of a 0.4000 %w/v solution of Ba(OH)2. How many grams of Ba(OH)2 will be needed to make the solution

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

Acontrol during an experiment. might change remains constant does not exist does change

Two metal blocks that have slightly different temperatures are placed next to one another. after five minutes, they both have lower but equal temperatures. according to the law of conservation of energy, what  most likelyhappened? energy was created inside the blocks.energy was destroyed inside the blocks.energy was absorbed into the blocks from outside the system.energy was transferred from the warmer block to the cooler block.