December 2019
Water and Salt Dance Party
When water and salt get together its like a dance party! When we mix salt with water there are ways we can use chemistry tricks to our human advantage… but that can turn into a party-gone-bad in certain situations too. Find out more here, even a tasty experiment ahead!
From snowy hillsides and skating rinks to lakeside docks and rivers to paddle; water is also a favorite place to play for many. Wonder with me a moment about water. Water is all around us in all seasons here in Minnesota. Water is a powerful chemical—even breaking some rules of chemistry.
But then we add salt to it. That changes things.
Too much salt in our food can affect our health. Salt permanently pollutes lakes and groundwater. Salt contaminates soil affecting where plants can grow.
4 Experiments Posted Here
Let’s get this party started with some hands-on learning about salt and water. May these salty experiences help you and your team (kids, students, family, friends) gain water/salt chemistry knowledge; then move that new knowledge into smart salting actions this winter.
All four experiments shared here are connected, but they do not need to be done on the same day. Starting with Salty Experiment #1 is recommended. This series of four “Salty Experiments” get at the following key ideas:
• Water and salt are amazing chemicals, both great at the dissolving process.
• Salt should be used wisely in what we eat and in melting icy streets.
• Stuff on earth, called matter, can exist in different forms. Most commonly solids, liquids, and gases that can switch to another form with temperature changes.
• A little salt goes a long way. Salt permanently pollutes water and soil.
• Changing our salt habits and sharing the facts about smart salting is something we can all take part in.
Background Information (scroll down for experiments)
Imagine a dance party when the music gets cranked up! People move, dance, mingle, and mix it up. Adding salt to ice drops the freezing point of water. This is like a dance party because the salt and water molecules are moving around, mixing together and the ice crystals of just water molecules don’t form as easily.
This lower freezing point of water which can reduce slick spots for pedestrians and cars. Salty water can act be a helper, like in our bloodstream. Salted water tastes differently. Aquatic life has adapted overtime to live in saltwater or freshwater habitats- with a select few critters that can do both. Adding salt to soil kills most plants- salting fields was an act of war in ancient times. Salted foods taste really good and salt can preserve food for long periods of time, but people with heart conditions must limit how much salt they eat.
When water and salt get together its like a dance party! The solid salt mixes quickly with liquid water, or more slowly with solid ice, and the H2O’s and NaCl’s get all mixed up and moving. Here’s why:
NaCl is the stuff in our salt shakers. There are many kinds of salts, but the most commonly used at home is also known as NaCl. The atoms of sodium (Na) bond ionically, or loosely share an electron, with chlorine atoms (Cl). With thousands and thousands of these NaCl’s together they naturally form a cubic crystal shape and the mineral we call halite. Pretzels, potato chips, and other yummy foods would not be the same without halite!
The H2O water molecules are able to pull an Na+ or Cl- close by to “dance” or mix into the liquid in a process called dissolving. Water is known chemically as H2O because it has 2 hydrogen atoms bonded with one oxygen atom. The oxygen atoms hang on to the hydrogen atoms in a “Mickey Mouse” shape by borrowing their electron. These hydrogen and oxygen atoms stay tight in H2O molecules, called a covalent bond. Each H2O group will still happily pull an Na+ or Cl-nearby to dance. In this way, water is powerful in dissolving. The water can gently pull the salt pieces apart, spreading it out like people on a dance floor dancing in a large mosh pit. From salt in snacks dissolving in your spit to salt on icy sidewalks, water and salt know how to work together like a silly dance party.
Guess what? Water can break the rules. Most liquids contract to fit into a smaller space when they freeze, but water expands when it freezes. This is the reason water floats as ice. Water is less dense as a solid than it is as a liquid. Most chemicals on earth do the opposite. If it weren’t for water breaking that rule, we wouldn’t be able to ice skate on ponds or go ice fishing!
Salty Experiment #1: Join the Water Dissolves Salt Dance Party
Put 1/4c water each into four glasses, all at room temperature. This works best if the glasses are the same. In the first glass, add no salt. In the second glass add 1 pinch of salt to the 1/4c water. Stir to dissolve the salt, then taste. In the third glass add 2 pinches of salt to the 1/4c water. The fourth and final glass add 3 pinches of salt to the 1/4c water. Next, in order of glass 1 through 4, take a sip from each glass. Then ask yourselves the questions below. Note: Please save the salted water for experiment #2.
Talk about these salty experiment #1 questions as a team:
When do you taste the salt?
Which do you feel is more of a superhero chemical, the water or salt? Why?
How does the phrase “a little goes a long way” apply here?
Which dance party (aka glasses 1 through 4) is best for the lake you like to swim in? Why?
Which dance party (aka glasses 1 through 4) is best for winter roads? Why?
In what ways could salt be recaptured or reused from the place it was put?
Get the Facts:
Research shows that 1 tsp of salt pollutes 5 gallons of water. https://www.pca.state.mn.us/water/chloride-salts
Minnesotans use 730 million pounds of salt on roads each winter.
https://www.mprnews.org/story/2017/12/06/road-salt-water-pollution
Salty Experiment #2: One Chemical is Last to Leave the Party
Pour the salted water from experiment #1 into a large glass or jar. Use tape or a pen to mark the water level. Place the jar uncovered in the sunlight for a week, checking the jar of salty liquid each day.
Watch for changes throughout the week. A chemical change means rearrangement of atoms to form a new substance. Most common signs of a chemical change are bubbles, strong color change, quick temperature change, or a strong odor. A physical change means the chemicals moved from one state of matter to another, like from a liquid to a solid or from a liquid to a gas. Record as a team what you notice and the questions you come up with on a paper nearby.
Talk about these salty experiment #2 questions as a team:
What role did the sun’s energy play in this experiment?
Where did the water go? Where did the salt go?
Which chemical evaporated (a physical change) from liquid to gas?
Which chemical got left behind as a solid (a physical change) at the dance party?
Was a new chemical created through chemical change? (No, just changed states fo matter)
Which do you feel is more of a superhero chemical in this experiment, the water or salt? Why?
In what ways could salt be recaptured or reused from the place it was put?
Get the Facts:
Minnesota Cities are Working to Use Less Salt
https://stormwater.pca.state.mn.us/index.php?title=Success_stories:_salt_reduction_and_cost_saving_examples
Salty Experiment #3: Tiny crystals can create BIG changes
Get a timer ready. Put 3 ice cubes on one plate. Put 3 ice cubes on a second plate. Add a pinch of salt to the top of the ice cubes on plate 2, but NOT plate 1. Set a timer as a reminder to check your plates every five minutes over the next half hour.
If a thermometer is available to you, take the temperature of the water/ice on each plate each time you check on your experiment. If you have a ruler, keep track of the ice cube height and how it changes over time. Collect data and your questions as a team. Data can be qualititaive or quantitiative. Qualitative data is words or stories to describe what you noticed. Quantitative data is numbers, such as the temperature or height of the ice cube.
Talk about these salty experiment #3 questions as a team:
Analysis means looking for patterns in data. What patterns did you see? In other words, what increased, decreased, or stayed the same?
Where was heat energy in this experiment compared to the last one?
Where did the water go? Where did the salt go?
Which chemical melted (a physical change) from a solid to a liquid?
Was a new chemical created through chemical change? (No, just changed states of matter from solid to liquid)
Which do you feel is more of a superhero chemical in this experiment, the water or salt? Why?
In what ways could salt be recaptured or reused from the place it was put?
Get the Facts:
Brining On Roads is Effective
https://www.accuweather.com/en/weather-news/rock-salt-vs-salt-brines-whats/22352942
How Salt Doesn’t Melt Ice- It Lowers the Freezing Point
https://www.scientificamerican.com/article/salt-doesnt-melt-ice-heres-how-it-makes-winter-streets-safer/
Salty Experiment #4: Plants are at the party too!
Choose three different vegetables that you are able to eat raw. Peel, slice, then divide the pile of vegetables in half evenly. Sprinkle one pile with salt and leave the other pile plain. Taste, from both piles, make observations, talk about it with your team. Next set the piles aside at room temperature for 15 minutes. After the time passes, taste again from both piles, make observations, and talk about it with your team.
Talk about these salty experiment #4 questions as a team: What changes took place? How did salt work with the water in the vegetables? How could salt spray effect trees, gardens, or lawns?
Knowledge to Action with Growing Green Hearts
Through your salty experiences and experiments, you’ve gained a lot of knowledge about salt and water. Next, use this list to move your knowledge to positive actions in care of our shared water resources. Ways help include:
• Notice businesses and organizations that do use salt minimally, wisely- and thank them.
• Download a salt tip card or salt smart poster for places you frequently visit.
• Use smart salting strategies where you live, work, and play.
• Visit the web link resources above to gain more facts about salt and water quality issues.
• Connect with the watershed district in which you live to attend a smart salting training.
• Advocate for smart salting practices with your local government, school, faith-based group and community clubs.
• Follow the CleanWaterMN.org blog and your local watershed district to gain information on ways to help water quality year round
Play. Learn. Love. Growing Green Hearts December 2019
