Colour­ful melt­ing ice

The Star Malaysia - Star2 - - BRIGHT KIDS -

THIS ex­per­i­ment ex­am­ines how quickly ( or slowly) you can melt ice us­ing salt and some wa­ter­colours.

It is a great fun learn­ing ac­tiv­ity for preschool- aged chil­dren to per­form on a hot day.

Chil­dren will not only learn sci­ence, they will also prac­tise their rea­son­ing and mo­tor skills. Make sure to ask ques­tions and dis­cuss what is hap­pen­ing to the ice as the ex­per­i­ment pro­gresses.

What you need:

• • • •

• • •

• Cake tin Wa­ter Salt Wa­ter­colours or food colour­ing Paint brushes Small spoons Large bak­ing dish ( op­tional)

Pre­pare ahead of time:

Freeze wa­ter in the cake tin. Re­move the block of ice from the tin for the ex­per­i­ment. Fill an ice tray with wa­ter. Mix in dif­fer­ent food colour­ings/ wa­ter colours to cre­ate a range

• of colours. Mix in some salt with each batch of coloured wa­ter. Place the block of ice on any sur­face or in a bak­ing dish to con­tain the melt­ing wa­ter.

What to do:

Pour some salt di­rectly onto the block of ice; it will pop and crack. Why does this hap­pen? Paint the block of ice with the wa­ter­colours. Does this speed up the melt­ing? Con­tinue paint­ing and sprin­kling salt onto the ice. Cracks will form, into which the wa­ter­colours will seep. Talk about what is hap­pen­ing and how it looks.

How it works:

Salt low­ers the freez­ing point of ice – where wa­ter usu­ally freezes at 0 C, it will now freeze at - 6 C ( with a 10% salt so­lu­tion).

This means that as the salt dis­solves into the wa­ter, it low­ers its freez­ing and melt­ing tem­per­a­ture, caus­ing the ice to melt more quickly than usual.

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