A sample of iron is heated from 15°C to 45°C and absorbs 1680 joules of energy. What is the mass of iron involved?

Calculate the molar mass of aluminum oxide (al2o3). express your answer to four significant figures.

An atom of sodium-23 (atomic number = 11) has a positive charge of +1. give this information, how many electrons does it have? how many proteins and neutrons does this atom have

0.09 moles of sodium sulfate in 12 ml of solution