In this case, for this calorimetry problem, since the acetylene is burned into the calorimeter causing a temperature increase, we can infer that the combustion of acetylene releases heat which is absorbed by the calorimeter, therefore, the following equation can be written:
Which can be written in terms of the energy of combustion and moles of the acetylene and the heat capacity and temperature change of the calorimeter:
Thus, since the molar mass of acetylene is 26.04 g/mol, the resulting energy of combustion of the acetylene turns out:
In this case, the required number on milligrams is:
It means that it has four significant figures which are counted for 7, 5, 0 and 2, considering that zero as it is to the right of first nonzero digit (7).
A (Hypothesis) is scientific knowledge published through direct observation and remains constant scientific knowledge can change when scientists (generate hypothesis)