Posted 10:57 a.m. Monday, Dec. 28, 2020
An understanding of chemistry can be a guide in selecting and applying ice melt
Winter is here, and with it, all the slipping and sliding. Keith Beyer, UW-La Crosse chemistry professor and Wisconsin native, lets basic chemistry guide to keeping his driveway and walkway slip-free.
Through chemistry we know that melting ice is a physical change that is caused by a chemical reaction. Salt is dissolving and turning into ions. It is doing that because it is interacting with the ice to form a salt solution.
What is in ice melt?
Many different products are available in stores. Bags or buckets labeled “ice melt” typically contain various combinations of active ingredients that work to melt ice such as calcium chloride, magnesium chloride and potassium chloride.
Often the most affordable ice melt you can purchase is the one you find on your dinner table —sodium chloride (NaCl). More commonly known as table salt, sodium chloride is also what is used in water softener. Beyer purchases the finer grain salt found in large cattle feed bags from the local farm supply store, mixing it with sand (for traction) before sprinkling it onto sidewalks and driveways. You can also buy sodium chloride in other forms like rock salt or salt used for water softeners, but a finer grain salt will allow you to distribute the salt more effectively for more melting. Note: Sodium chloride works best in temperatures of about 10 degrees Fahrenheit and above. If the temperature dips below that, you’ll want to consider another option.
What ice melt to use in colder temperatures?
When the temperature dips below 10 degrees Fahrenheit, ice melt products will work better than pure sodium chloride. Ice melt is typically a blend of different salts that melt ice at different temperatures. Common ingredients are calcium chloride and magnesium chloride. Beyer didn’t have a preference for one type of salt combination over another. But be sure to read the label to find out the temperature range for the ice melt you are purchasing.
What is a pet-safe ice melt?
If you are concerned about pets or plants being near or consuming salts, another option is urea. This is a component of fertilizer and is often available at hardware and farm supply stores. Urea will also work to melt ice, and it is non-toxic and pH neural. However, it will not melt the ice as effectively as salts, so more would need to be used to get the same effect.
What makes ice melt work faster?
Using small grains of salt instead of large granules allows the salt to touch more surface area of the ice, thus melting more. This is the most important factor to speed up how quickly ice melt works on a surface. Small grains also allow you to cover more area with less salt.
Will products work differently on different surfaces?
Products work about the same on all surfaces whether concreate or asphalt. Some salts may cause some degradation of these surfaces, but the effects would be so small that Beyer would not hesitate using them. If you are concerned about salt damaging a surface, scrape away excess salts as they build up over the course of the winter.
People may observe ice melting faster on metal, but it does not. This may be because of other reasons such as a car being warm from recently running or a metal roof melting quickly because of its dark color or sun exposure.
What temperature does ice melt?
32 degrees Fahrenheit
Tips to help ice melt work more effectively
- Mix sand with the salt for traction. It can also help grind up ice that is not yet melted.
- Use finely ground salt like the kind used for cattle feed to cover more surface area. Where the salt touches the ice is where the melting will occur.
- Have patience. Melting won’t happen instantaneously when you apply salt. Sprinkel some and then wait about 30 minutes. Then, sprinkle more if needed. This will also help you gauge how much you really need and not waste.
- Try using a zigzag pattern when spreading ice melt on a slope. This will allow you to cover more surface area with less as the melting begins and trickles down the slope.