Nappies Coursework

Aim: Find out if more expensive nappies are more absorbent, and therefore worth the extra money.

Standard Procedure:

1. Cut 5 x 5 cm sized sample from the absorbent section of each nappy.
2. Weigh each square in grams
3. Add liquid to the nappy square in equal amounts
4. Stop adding liquid when the nappy leaks
5. Record the volume of liquid added
6. Re-weigh the nappy square
7. Record your measurements in a table

Nappy Information:

The active compomnet in the absorbant part of the nappy is Sodium Polyacrylate.

Brand	Pack Size	Pack Price	Total Absorbant Area
Boots	48	£ 3.79	330 cm² (10 x 33 cm)
Huggies	27	£ 2.79	270 cm² (10 x 27 cm)
Pampers	27	£ 3.72	270 cm² (9 x 30 cm)
Tesco	24	£ 1.64	360 cm² (10 x 36 cm)

Synthetic Urine Recipe:

1000 ml Water 20g Table Salt

20 ml 0.5 mol Ammonia solution 5 drops of Yellow food colouring

What to include in the write up:

Introduction

• Background to nappies eg contain colloid - explain why disposible nappies are more comfortable for babies than reuseable Terry Towel nappies . Add research into nappies
• Explain why the practical activity is useful in a workplace that uses science (how are results used and benefits of results). Give examples of the types of organisation that use this type of activity.

• Copy in the standard procedure.
• Fill in the equipment list
• Complete a risk assesment (chemical and physical hazards)

Analysis

• Calculate mass of urine absorbed by the sample
• Calculate price per nappy
• Calculate total absorbancy for each nappy - the amount of urine each could hold (mass and/or volume) based on your findings for 25 cm²

  Total absorbancy	=	Amount of urine absorbed by sample	×	Total absorbancy area
  		Area of sample

• Either add this to your table or create a new table
• Plot Total Absorbency against cost in a hand drawn scatter graph with a line of best fit
• Write a conclusion to include:
  • Which nappy held most urine?
  • What is the relationship between cost and absorbancy
  • Does this nake it worth buying expensive brand nappies?
  • What other considerations, as well as absorbency, should be considered when buying nappies?

• Write a brief method for your experiment, paying attention to how you made it fair, accurate and reliable.
• How fair, accurate and reliable were your results?
• Discuss any odd (anomalous) results
• How could you improve your results? Explain why this would improve (other than do more repeats)
• What would you do differently?
• What other experiments could you do to extend this investigation? (Think about the other considerations when buying nappies - how could you test these?)