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3 years ago

13. Calculate the total heat energy in Joules needed to convert 20 g of substance X from -10°C to 70°C?

1 answer:

5 0

The heat required to convert the unknown substance X from one phase to another is 1600 J times the specific heat of that substance.

Explanation:

The heat energy required to convert a substance or to heat up or increase the temperature of a substance can be obtained from the specific heat formula.

As per this formula, the heat energy applied should be equal to the product of mass of the substance with temperature gradient and also with specific heat of the substance. Basically, the heat provided to increase or convert a substance should be more than the specific heat of the substance.

$Q = mc del T$

Since, here the mass of the substance X is given as m = 20g and the temperature change is given from -10°C to 70°C.

Then ΔT = (70-(-10))=70+10=80°C.

As the substance is unknown, the specific heat of that substance can also not be determined. Hence keep it as C.

$Q = 20*C*80$

Q = 1600C J

Thus, the heat required to convert the unknown substance X from one phase to another is 1600 J times the specific heat of that substance.

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The potential energy of a 2-μc charge at that point in space is $8*10^{-4}$ joules.

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<h3>Potential energy</h3>

The energy that an item retains due to its position in relation to other objects, internal tensions, electric charge, or other reasons is known as potential energy in physics. The gravitational potential energy of an object is based on its mass and the distance from the centre of mass of another object. Other common types of potential energy include the elastic potential energy of an extended spring and the electric potential energy of an electric charge in an electric field. The joule, denoted by the sign J, is the SI's definition of an energy unit.

The vectors that are described as gradients of a particular scalar function known as potential can be used to represent these forces, also known as conservative forces, at any location in space.

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2 years ago

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3 years ago

An aluminum calorimeter with a mass of 100 g contains 250 g of water. The calorimeter and water are in thermal equilibrium at 10

Nadya [2.5K]

Answer:

1822.14 J/kg C

Explanation:

Mass of aluminum = 0.100 kg

Mass of Water = 0.250 kg

Mass of copper = 0.300 kg

Mass of unknown object = 0.70 kg

Initial temperature of Aluminum = 10 C

Initial temperature of water = 10 C

Initial temperature of copper = 30 C

Initial temperature of = 100 C

Final temperature of all substances = 20 C

Change in temperature of each of them Aluminum, water , copper and unknown material respectively = 10 C , 10 C , -10 C, -80 C respectively

Specific heat of each of them Aluminum, water , copper and unknown material respectively = 900,4186,387 and c respectively.

Heat gained by aluminum and water = (0.1)(900)(10) + (0.250)(4186)(10) = 11365 j

heat lost by copper and unknown material =(0.3)(387)(-10) = -1161

heat lost by unknown material = (0.070)(c)(-80) = -5.6 c

Now solve for c using the calorimetry principle.

Heat lost + Heat gained = 0

⇒ -5.6 c = -11365 - (-1161) = -10204 j

Specific heat of unknown material = - 10204 / -5.6

= 1822.14 j/kg C

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