Question

1) How much heat must be supplied in joules to raise the temperature of 50 grams of Iron from 25C to 100C?

2) Calculate the dimensions for a pattern mold that will be used to produce a cast rectangular shaped Gold ingot with dimensions of 10 x 10 x 3 cm at 25C.

Answer 1

Solution- (1) Data given, Mass of iron,m 50g Temperature T, 25°C TemperatureT 100°c Consider that the specific heat capacity of iron is Cf Heat required to raise the temperature is 0.450 J/g°C q = mCF,AT q (50) (0.460 J/g °C) (100-25) q 1725J tacnces thr betreguired io sise the temperanuris17s Calculate the dimensions for a pattern mold that will be used to produce a cast rectangular haped Data given, Gold ingot with dimensions of 10 cmx10 cmx 3 cm To produce a casting having particular final dimensions, the mold cavity into which the liquid Gold, the solid casting contracts as it cools to room temperature. If we calculate the amount of contraction expected, we can make the original pattern used to produce the mold cavity that much larger,

Assume the linear coefficient of thermal expansion for Gold is 19.3x10 C The temperature change from the freezing temperature to 25 C is ΔΤ-1063-25 - 1038 °C The change in any dimension is given by, Δ1-10-If For the 10 cm dimensions, 1-10 cm We wish to find 10 - o-10 - (19.3x10*) (16)(1038) 10.20 cm For the 3 cm dimension, - 3 cm 10-3-(19.3×10-6)(1.)(1038) 1 3.06cm If we design the pattern to the dimensions 10.20 cm×10.20 cm×3.06 cm , the casting should contract to the required dimensions.