Define molality and mole fraction.

A solution is prepared by dissolving 2g of a substance A to 18g of water. Calculate the mass percent of the solute.

Calculate the molarity of NaOH in the solution prepared by dissolving its 4g in enough water to form 250mL of the solution.

A solution is prepared by dissolving 5.3g of Na₂CO₃ in distilled water to give 500 mL of solution. Calculate the molarity of the solution.

216.

A sample of NaNO₃ weighing 0·38g is placed in a 50·0 mL volumetric flask. The flask is then filled with water to the mark on the neck. What is the molarity of the solution? 

A sample of NaOH weighing 0.38g is dissolved in water and the solution is made to 50.0 mL in a volumetric flask. What is the molarity of the resulting solution? 

How many moles of NaOH are contained in 27mL of 0.15 M NaOH?

How are 0.50 mol Na₂CO₃ and 0·50 M Na₂CO₃ different?