An unknown mass of water at 18.2°C is added to 24.9 g of water at 35.0°C. If the final temperature is 23.5°C, what was the unknown mass? (Assume that no heat is lost to the surroundings.

Respuesta :

72.353g is the mass of water at 18.2°C is added to 24.9 g of water at 35.0°C. If the final temperature is 23.5°C.

What is specific heat capacity?

The specific heat capacity is defined as the quantity of heat (J) absorbed per unit mass (kg) of the material when its temperature increases 1 K (or 1 °C), and its units are J/(kg K) or J/(kg °C).

The final temperature is closer to the temperature of the colder water sample than it is to the temperature of the warmer sample.

This means that you can expect the volume of the colder sample to be bigger than that of the warmer sample.

Now, you will need to use the density of water to determine the mass of the warmer water sample. You can find the density of water at different temperatures here:

So, at 35.0∘C, water has a density of approximately 0.994 g/mL

This means that the warmer sample has a mass of:

33.5 mL x [tex]\frac{0.994 g}{1 mL} = 33.3 g[/tex]

Now, your tool of choice will be the equation that establishes a relationship between heat gained or lost and change in temperature.

q - the amount of heat

m - the mass of the sample

c - its specific heat, in your case equal to 4.18 J /g∘C

ΔT - the change in temperature, defined s final temperature minus initial temperature

The key to this problem is the fact that the heat lost by the warmer sample will be equal to the heat gained by the colder sample.

[tex]-q_{lost} =q_{gain}[/tex]

[tex]-m_{cold}[/tex] . c .ΔT = [tex]m_{warm}[/tex] . c .ΔT[tex]_{warm}[/tex]

The minus sign is needed because heat lost carries a negative sign as well.

Plug in your values into the above equation and solve for [tex]m_{cold}[/tex]

[tex]m_{cold}[/tex] = 2.1698 ⋅ 33.3 g

= 72.25 g.

To get the volume of the colder sample, use water's density at 18.2∘C, which is approximately 0.99856 g/mL.

72.25 g x [tex]\frac{1 mL}{0.99856 g} = 72.353g[/tex]

72.353g is the mass of water at 18.2°C is added to 24.9 g of water at 35.0°C. If the final temperature is 23.5°C.

Learn more about specific heat capacity here:

#SPJ1

Otras preguntas