Change in enthalpy equation If the formula for change in enthalpy is ΔH=ΔU+pΔV, and ΔU = q - pΔV then shouldn't the formula be simplified to ΔH = q regardless of whether the volume or pressure is constant? Is this only true when pressure and volume is constant?
The general formula is $\Delta H=\Delta U + \Delta (pV)$.

Since $\Delta U=q_v$ (heat at constant volume), then $\Delta H=q_V+V\Delta p$, so no, heat at constant volume does not equal enthalpy, unless p is constant, which just brings you back to the original relation $\Delta H = q_p$.