Skills for Study Level 2 Teacher's Book - Cambridge University Press

4fAnswers3.6StepPosition in sequencea Set up the Büchner flask, funnel, pipe, and aspirator 1b Empty the crystals onto a piece of filter paper andleave them to dryc Shake the mixture 3d Pour the test tube mixture into the Büchner funneland apply suctione Create a vacuum in the Büchner flask 4f Add 5 ml of water to the test tube 2654g Student discussionAnswersA vacuum can be created in a Büchner flask by attaching it to a tap using alength of rubber pipe and an aspirator; water flowing through the aspiratorproduces a vacuum. The suction on the Büchner flask should be broken bydisconnecting the pipe from the flask. If the suction is broken by turning off thewater at the tap, then any water that remains in the pipe may flow back into theflask. The student probably broke the suction by turning off the water at the tapinstead of disconnecting the pipe.4h See 4i for answers.4iAnswers3.7StepPosition in sequenceLeave the solution to cool 3Heat the solution until the crystals dissolve 2Put the dry crystals into a beaker and add water 14j Students check their answers.4k Student discussionAnswersThey were only supposed to add 3 ml of water, not 30. The solution is probablytoo dilute for the aspirin to form out of it.Unit 3 Part A ∙ Understanding spoken information 79