A 644.0 g sample containing magnesium sulfate and inert material was dissolved and treated with (NH4)2HPO4 to precipitate the magnesium as MgNH4PO4. 6H2O. After being filtered and washed, the precipitate was ignited at 10500C to Mg2P2O7 that, upon cooling, weighed 293.0 mg. Calculate the % Mg in the sample.

3. The microstructure of a Cu-Ag alloy at 779°C consists of primary a (with mass fraction of 0.73) and eutectic structure (with mass fraction of 0.27). Determine the composition of this alloy. Temperature (°C) 1200 A 1000 Ⓒ 800 600 400 200 a C (Cu) B 8.0 (CE) -Solidus Solvus 20 20 a +L Composition (at% Ag) 40 -Liquidus 779°C (T) a+B 40 60 Composition (wt% Ag) T Liquid 60 71.9 (C₂) 80 80 B+L 91.2 (Cpg) 100 T 2200 G TITINTI B ++ H 2000 1800 F 1600 1400 1200 1000 800 600 400 100 (Ag) Temperature (°F)

A sample of sucrose, C12H22O11, is contaminated by sodium chloride. When the contaminated sample is burned in a bomb calorimeter, sodium chloride does not burn. What is the percentage of sucrose in the sample if a temperature increase of 1.50°C is observed when 3.000 g of the sample is burned in the calorimeter? Sucrose gives off 5.64×103 kJ/mol when burned. The heat capacity of the calorimeter and water is 22.51 kJ/°C. _____________ %