Does hot water really freeze faster than cold water?
Yes — a general explanation. Hot water can in fact freeze faster than cold water for a wide range of experimental conditions. This phenomenon is extremely counterintuitive, and surprising even to most scientists, but it is in fact real. It has been seen and studied in numerous experiments.
Why does hot water freezes faster than normal water?
If the water is initially hot, cooled water at the bottom is denser than the hot water at the top, so no convection will occur and the bottom part will start freezing while the top is still warm. This effect, combined with the evaporation effect, may make hot water freeze faster than cold water in some cases.
Does hot water or cold water freeze faster and why?
Why hot water freezes faster. When water is frozen, a similar reaction happens. The molecules initially tighten up and bind together to create a solid form. Since hot water’s molecules are already tightened up, it has a head start on looking it should in its frozen state. Cool water would take time to reach this point.
What freezes faster, hot water or cold water?
You Will Need:
- One cup of cold water, 100mL in volume
- One cup of hot water, 100mL in volume
- One Stopwatch
- One Stirrer
- A freezer
- A pen and paper
Does hot or cold water boil faster experiment?
The claim is repeated so often that many people accept it as fact. But according to scientists, the notion that a body of cold water will reach boiling temperature more quickly than an identical body of hot water under the same parameters is simply false.
Which liquid freezes the fastest science project?
Water freezes fastest because water doesn't contain other ingredients. Water is H2O, hydrogen and oxygen.
Which theory states that hot water freezes faster than cold water?
Mpemba effectThe Mpemba effect is the name given to the observation that a liquid (typically water) which is initially hot can freeze faster than the same liquid which begins cold, under otherwise similar conditions. There is disagreement about its theoretical basis and the parameters required to produce the effect.
What freezes first water or juice?
The sugar molecules are not the same shape or size as the water molecules are, so they don't fit into the ice crystals, even though they do fit nicely into the liquid water. Because of this, it's actually harder to freeze liquids like juice or soda than plain water - you have to get them colder before they will freeze.
What freezes first water or salt water?
Which freezes faster, water or salt water? Answer 1: While pure water freezes at 0°C (32°F), salt water needs to be colder before it freezes and so it usually takes longer to freeze. The more salt in the water, the lower the freezing point.
Why do hot water lines freeze first?
If the water is initially hot, cooled water at the bottom is denser than the hot water at the top, so no convection will occur and the bottom part will start freezing while the top is still warm. This effect, combined with the evaporation effect, may make hot water freeze faster than cold water in some cases.
How does Mpemba effect work?
His experiments revealed that the Mpemba effect occurs when ice crystals appear in a supercooled liquid at higher temperatures, which means that, in such cases, hot water would appear to freeze first.
Will hot water pipes freeze before cold water pipes?
It is a strange thing that hot water pipes freeze quickly than cold water pipes. By increasing the temperature of your house, you can attempt to unfreeze the frozen pipe.
Which liquids freeze faster?
Different liquids freeze at different temperatures. Water will freeze faster than liquids with salt or sugar in them.
What is the easiest liquid to freeze?
Water froze in an average of 56.7 minutes. Vinegar froze in an average of 63.3 minutes. Soda had an average of 90 minutes, milk had an average of 86.7 minutes, and dish soap had an average of 93.3 minutes.
What chemical freezes instantly?
liquid nitrogenIn physics and chemistry, flash freezing is the process whereby objects are frozen in just a few hours by subjecting them to cryogenic temperatures, or through direct contact with liquid nitrogen at −196 °C (−320.8 °F). It is commonly used in the food industry.
Which liquids can freeze?
Freezing point - the temperature at which a liquid turns into a solid....Common fluids and their freezing and melting points.FluidFreezing and Melting Point (K)Benzene278.7Benzonitrile260.3Bromine265.95Bromobenzene242.448 more rows
Brief summary
Students will participate in or observe a simple experiment to find out whether hot or cold water freezes fastest.
What to do
Step 1. Take your two foam cups and label one "hot" and the other "cold".
How does it work?
Known as the Mpemba effect - after a Tanzanian student who noticed that hot ice cream mix freezes faster than a cold - it was in fact first observed by Aristotle, then later Francis Bacon and René Descartes. But while
Why does it take more time to freeze hot water?
It will actually take more time and/or energy to freeze hot water because it must be brought down further in temperature until it reaches the freezing point, about 0 ° C . Govindan suggests conducting a simple experiment to demonstrate that hot and cold water will behave as logic predicts.
What temperature does water have to be to form ice crystals?
When the temperature of the water in each container reaches just about 0 ° C it will undergo the same changes as it moves from a liquid to a solid, and it will take the same amount of time to begin forming tiny ice crystals.
Does hot water freeze faster than cold water?
It’s an age-old question with a simple answer: no. Since the time of Aristotle, researchers and amateur scientists alike have batted about the counterintuitive theory that hot water freezes faster than cold.
Why does cold water turn into ice before hot water?
It makes sense to believe that cold water would turn to ice before hot water because the hot water would need to cool first before it could freeze; but how do you know if that idea is correct? Test this theory —untested idea—will tell you whether cold water actually freezes faster than hot water.
How to make a notebook with a hot water bowl?
Pour it into the Hot bowl, being careful not to burn yourself. Heat 1 cup of water to 70 degrees Fahrenheit, and pour it into the Warm bowl. Fill the Cold bowl with water that's 40 degrees Fahrenheit. Immediately place all three bowls in the freezer. Record the starting temperatures in the correct columns of your notebook.
Does hot water evaporate faster than cold water?
First, all water evaporates, which means that the liquid (water) "disappears" and becomes a vapor, or gas. Hot water evaporates at a much faster rate than cold water. This means that the bowl with hot water actually had less water than the bowl with cold water, which helped it freeze more quickly.
What is the effect of water cooled in a freezer?
When the sample containing the hotter water is placed on a shelf, in the freezer, the heat will melt the ice under the container . When this re-freezes there will be a better conductor of the heat away from the container than the sample ...
Why does water at the surface of a sample behave differently?
Because the water at the surface is less dense that the water beneath the frozen layer will stay at the surface and form a insulating layer for the water beneath. The hotter sample will behave differently. The water at the surface will cool rapidly due to evaporation, and will become denser that the hot water below.
Why is evaporation important?
Evaporation — this is important if the temperature of the water sample is high and the container has a large exposed surface area. Evaporation has the effect of removing mass from a high temperature sample, which will then compensate for the greater temperature range. Convection — water is at its most dense at 4 °C.
Why does water sink to the bottom of a container?
The water at the surface will cool rapidly due to evaporation, and will become denser that the hot water below. The denser surface water will then sink to the bottom of the container and push the hotter water to the surface.
What is the phenomenon of hot water freezing faster than cold water?
As the video above explains, the phenomenon of hot water freezing faster than cold water is known as the Mpemba effect , named after Erasto Mpemba, a Tanzanian student who in 1963 was making ice cream as part of a school project. The students were meant to boil a mixture of cream and sugar, let it cool down, and then put it in the freezer.
Who first observed that hot water cooled sooner than cold water?
It was the first peer-reviewed study on the effect, but as Derek notes in the video above, observations date all the way to Aristotle in the 4th century BCE, who observed that hot water cooled sooner than cold during his experiments. Sir Frances Bacon and Descartes also noted the phenomenon in their studies.
How long did it take Mpemba to freeze his mixture?
Worried about getting a spot in the freezer, Mpemba instead put his mixture in while it was still scorching hot. But after 1.5 hours, his mixture had frozen, while his classmates' mixtures had not.
Why does hot water cool faster?
Convection: Finally, there's the idea that warm water might cool faster due to increased convection currents. These currents occur because water cools primarily from its surface and the sides of the beaker, ...
Why does water freeze at zero degrees Celsius?
This occurs because ice needs a nucleation site, such as an air bubble or impurity in the water in order to form.
Do warm beakers affect cooling?
The currents are greater in warm beakers, and could affect cooling rates. There's merit in all those ideas, but the problem is that experiments over the years have controlled for all these effects, and the results have been frustratingly inconsistent.
Does hot water freeze faster than cold water?
It seems obvious that the answer should be no, because all things being equal, hot water takes longer to cool down than cold water, and so it couldn't possible freeze faster. But observations over thousands of years, as well as countless modern experiments, have shown that the opposite is true - under carefully controlled conditions, ...
