mass concentration

Question 1

mass concentration (g dm-3)

Answer 1

mass/volume

Question 2

how do you turn concentration measured in mol dm-3 into conc. measured in g dm-3

Answer 2

multiply by the Mr of the substance

Question 3

ions dissociating

Answer 3

when soluble ionic solids dissolve in water they will dissociate into separate ions. this can lead to the concentration of ions differing from the concentration of the solute.

Question 4

making a solution

Answer 4

• weigh the sample bottle containing the required mass of solid on a 2 dp balance
• transfer to beaker and reweigh sample bottle
• record the difference in mass
• add 100cm3 of distilled water to the beaker. use a glass rod to stir to help dissolve the solid
• pour solution into a 250cm3 graduated flask via a funnel
• rinse beaker and funnel and add washings from the beaker and glass rod to the volumetric flask
• make up to the mark with distilled water using a dropping pipette for the last few drops
• invert flask several times to ensure uniform solution