What Is the Correct Mass of Water When Hot Copper Meets Cold Water?

In summary, the conversation discusses a problem involving the mass and temperature of copper and water. The solution involves using the specific heat capacity of copper and the equation m1c1 delta T1 = -m2c2 delta T2 to find the mass of water in the container. However, the computer and manual calculations do not give the same answer, leading to frustration and confusion. The issue may be related to significant digits or an error in the numerical calculation.
  • #1
Pengwuino
Gold Member
5,123
20
hot metal + water = Tf?

Yet again I find i am stumped by having no clue as to what I did in this incredibly easy problem.

A 110.-g sample of copper (specific heat capacity = 0.20 J/ºC•g) is heated to 82.4 ºC and then placed in a container of water at 22.3 ºC. The final temperature of the water and copper is 25.6 ºC. What is the mass of the water in the container, assuming that all heat lost by the copper is gained by the water?

Simple right?

1 = water
2 = copper

m1c1 delta T1 = -m2c2 delta T2

This simplifies to...

m1= (-m2c2 delta T2)/(c1 delta T1)

which is...

(-(110*.2*(25.6-82.4)))/((4.18*(25.6-22.3)) = 95.8533g

Computer says I'm wrong and it slapped me

I then did the lazy way and calculated the energy required to lower the copper's temperature. With that, I manually figured out how much water there was and got the exact same answer.

Where am I going wrong here?
 
Last edited:
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  • #2
Significant digits? I don't know... :confused:
 
  • #3
Did you do your numerical calculation right? Isn't the answer 90.59 g?
 
  • #4
I tried 3 and 4 sig. figures with +/- 1 each direction and nothings coming out correctly. God i want to pound the writers of this textbook.
 

FAQ: What Is the Correct Mass of Water When Hot Copper Meets Cold Water?

1. What happens when hot metal is added to water?

When hot metal is added to water, a chemical reaction occurs. The heat from the metal causes the water molecules to move faster, resulting in the metal breaking down into smaller pieces and releasing gases. This reaction can also generate a lot of heat, potentially causing the water to boil or even explode.

2. Why is it dangerous to mix hot metal and water?

Mixing hot metal and water can be dangerous because of the potential for a chemical reaction to occur. The sudden release of heat and gases can cause the water to rapidly boil and potentially cause burns or explosions. Additionally, the metal may break down into smaller pieces that can be sharp and cause injury.

3. What is the Tf value in the equation "Hot metal + water = Tf"?

The Tf value refers to the temperature at which the hot metal and water reach equilibrium. This means that the heat from the metal and the heat from the water are equal, and the temperature stops rising. This temperature can vary depending on the type of metal and amount of water present.

4. Can hot metal and water be safely mixed under any circumstances?

In general, it is not recommended to mix hot metal and water as it can be dangerous. However, in certain controlled situations, such as in industrial processes, hot metal and water may be safely mixed if proper safety precautions are taken and the reaction is closely monitored.

5. Is the reaction between hot metal and water exothermic or endothermic?

The reaction between hot metal and water is considered to be exothermic, meaning it releases heat. This is because the heat from the metal causes the water to heat up and potentially boil. However, depending on the amount of water present and the type of metal, the reaction may also have endothermic aspects as some water molecules may be consumed in the reaction, resulting in a decrease in temperature.

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