²⁹An important detail to note is that specific heat does not remain constant over wide temperature changes. This complicates calculations of heat required to change the temperature of a sample: instead of simply multiplying the temperature change by mass and specific heat (Q = mcΔT or Q = mc[T₂ − T₁]), we must integrate specific heat over the range of temperature (Q = m∫ _T1^T₂c dT), summing up infinitesimal products of specific heat and temperature change (c dT) over the range starting from temperature T₁ through temperature T₂ then multiplying by the mass to calculate total heat required. So, the specific heat values given for substances at 25 ^oC only hold true for relatively small temperature changes deviating from 25 ^oC. To accurately calculate heat transfer over a large temperature change, one must incorporate values of c for that substance at different temperatures along the expected range.