1. Potassium persulphate is used in photography to remove the last traces of unwanted chemicals from photographic papers and plates. A 0.8162 g sample was found to contain 0.2361 g of potassium, 0.1936 g of sulphur and the rest was oxygen. What is the empirical formula of this compound? Prove with calculations.

Use the table to identify the phase and phase changes of the elements under the given conditions. write the name of the substance, phase, or phase change. when the temperature in a room increases from 25°c to 33°c, changes from a solid to a liquid. in a lab, methane and nitrogen are cooled from -170°c to -200°c. the methane freezes and the nitrogen . when gold is heated to 2,856°c it changes from a liquid to a .

Freezing and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.

Using the first volume and temperature reading on the table as v1 and t1, solve for the unknown values in the table below. remember to use the rules of significant figures when entering your numeric response.