It is sometimes necessary to produce saturated steam from superheated steam (steam at a temperature higher than the vapor-liquid coexistence temperature at the given pressure). This change can be accomplished in a desuperheater, a device in which just the right amount of water is sprayed into superheated steam to produce dry saturated steam. If superheated steam at 3.0 MPa and 500^◦C enters the desuperheater at a rate of 500 kg/hr, at what rate should liquid water at 2.5 MPa and 25^◦C be added to the desuperheater to produce saturated steam at 2.25 MPa?