Water, water everywhere!

In this session we will start to investigate the question –

  1. What is the water cycle?

What should I be able to do at the end of this investigation? I should be able to …

  1. Construct different types of data displays and predict patterns.
  2. Describe and interpret different data sets.
  3. Communicate ideas, explanations and processes in a variety of ways, including multi-modal texts.
  4. Accurately observe, measure and record data using digital and non-digital technologies.
  5. Apply my understanding of the model to explain what the water cycle is.

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Meet H2O!

Water_molecule_(1).svg It’s the molecule which sets Earth apart from all other planets. Yes, evidence of water has been found on Mars, but it’s not present in same form as on Earth. Earth has two main types of water. Salty sea water makes up about 97% of all water on Earth, while the other 3% is fresh water, which is mainly stored as frozen water in ice sheets.

We are going to conduct an experiment that will help us to understand the forms of water on Earth and how they can change from one type to another in what is commonly referred to as the water cycle.

You will need;

  • a beaker half full of ice
  • access to a mass balance
  • 1 watchglass
  • 1 thermometer
  • 1 hotplate
  • Your laptop with a new Excel document set up and saved as “Water Cycle experiment”.

For this experiment you will work in groups of two. One person will read the thermometer for half of the time, while the other will be recording the data into Excel. Swap over roles half way through the experiment so you have practise at doing both.

Set up your equipment as shown below.

IMG_2230

NOTE; When recording your data DO NOT LET the bottom of the thermometer touch the bottom of the beaker. Keep the thermometer in the middle of your ice! When conducting this experiment each member of the group MUST WEAR safety googles. Remember – they are not a fashion statement but a piece of safety equipment to protect your eyes from boiling water.

Measure the mass of your beaker and ice.

Record the original temperature of the ice. Do this quickly but make sure that the temperature is stable before recording the value. Why would you do this? Record the temperature in the time = 0 cell. Your data table should have three columns:

Time (minutes)     Temperature (degrees Celcius)     Observations

Record the temperature every minute up to five minutes after your water has begun to boil vigourously. Remember to record any observations that you notice. Do this in an “Observations” section on your data table.

After your equipment has cooled down record its mass again.

Plot your data. What type of graph is appropriate to use here? What are the other features of a graph that you need to include? In your blog, start a new post entitled “Water, water everywhere” (we’ll learn how to shift it to our STEM page at a later date). Answer the questions below, making sure that you follow the guidelines “Writing complete answers” found on the tab on the STEM page. Once you have finished recording the data, switch off the hotplate and let the equipment cool.

What happened to the ice as heat was applied? Did the mass of the system change before and after the experiment? Give reasons for your answer.

Look at the word list below. What did you observe in your experiment that relates to these words? For example, the ice you used would be related to the Earth’s icecaps, so you would write

         ice = icecaps

 ice, Sun, evaporation, oceans, clouds, snow, rain, ocean currents, condensation, transpiration

If you are not sure what a word means then visit this look it up .

The experiment that you just did gives us a model of the water cycle. Scientists often use models to explain how things happen. Using the terms above write a short descriptive paragraph explaining how water goes through a cycle on Earth. Use words such as; energy, heating, cooling, rain, clouds, evaporation or evaporate or evaporating, condensation or condensing or condensate.

How closely were you observing what was happening in the beaker. Below is a short clip that was taken after all the ice has melted but before boiling has occurred. Look closely. What can you notice? What do you think is happening and why?

 

Okay, so we have looked at the water cycle. How about we do a recap on the topic.

If you would like to investigate the water cycle more then go to the South East Water website.

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