Answer:
Sample A is a pure substance
Sample B is a mixture
Explanation:
We are told that the when the yellow solid, sample A is ground it turned to orange colour and was then dissolved. Some part of the solid settled out at the bottom of the beaker while some part floated on top of the water. 50g of the solid was dissolved and 50.1g of the solid was recovered.
This implies that the substance is pure since the mass dissolved was almost the same mass recovered. The 0.1g addition in mass may result from incomplete drying of the solid.
For sample B, the distillation of the sample of density 0.77 g/ml left a fraction in the beaker with density 1.04 g/ml indicating that the substance is a mixture. Different components of a mixture possess different densities.
Answer: Multiply the volume and pressure and divide the product by the temperature and the molar gas constant to calculate moles of the hydrogen gas. In the example, the amount of hydrogen is 202,650 x 0.025 / 293.15 x 8.314472 = 2.078 moles.
They contain metals with the acception of Hydrogen (nonmetal)
