How many joules of heat are given off when 50 g of liquid water at 30℃ freezes to ice?

In apex! a liquid heated beyond a certain temperature becomes

In a heat engine of 1000 j of heat enters the system and the piston does 500 j of work what is the final internal energy of the system if the inital energy was 2000 j we have to do all of these down here 1)write the equation 2)list out your know variables 3)plug the numbers into the equations 4)solve 5)write your solution statemtn that includes inital energuy and final energuy added

Calculate the percent composition by mass of each element in al(oh)3. use at least three significant figures.