negative , because the reaction is endothermic

positive , because the reaction is endothermic

positive m because the reaction is exothermic

Science Quiz [ Mr, Shokir ]

2.

Using the quantity of heat equation , what would the formula look like if we were calculating the change in temperature ? ........

Q_p.m=Δ T.c
Q_p/m.c=Δ T
Q_p.m/c=Δ T
Q_p.c.m=Δ T

Correct Answer

A. Q_p/m.c=Δ T

Explanation

The formula for calculating the change in temperature using the quantity of heat equation is qp/m.c=Δ T. This formula represents the change in temperature (Δ T) as the quotient of the heat absorbed or released (qp), the mass of the substance (m), and the specific heat capacity (c). By dividing the heat by the product of the mass and specific heat capacity, we can determine the change in temperature.

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3.

Dissolving process is called hydration when the solvent is ..........

Benzene
Oil
Alcohol
Water

Correct Answer

A. Water

Explanation

The dissolving process is called hydration when the solvent is water. This is because water has a unique ability to dissolve many substances due to its polar nature. When a solute is dissolved in water, the water molecules surround and separate the solute particles, resulting in a homogeneous mixture. In contrast, benzene, oil, and alcohol are nonpolar solvents and do not undergo hydration when dissolving solutes.

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4.

If the heat content of products is lower than that of reactants , thus the reaction ...........

Is endothermic
Is exothermic
Whose Δ H value has a positive sign
Whose Δ H value = zero

Correct Answer

A. Is exothermic

Explanation

If the heat content of products is lower than that of reactants, it means that heat is being released or given off during the reaction. This indicates an exothermic reaction, where energy is being released to the surroundings.

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5.

The following is a list of specific heat capacities for a few metals : C copper = 0.385 , C iron = 0.444 , C silver = 0.240 , C aluminum = 0.900 50 g of sample on an unknown metal is heated with 800 joules , if the temperature of the metal increases by 41.6 C , What is the identity of the unknown metal ? ................

Copper
Silver
Alumnium
Iron

Correct Answer

A. Copper

Explanation

The specific heat capacity of a substance is the amount of heat energy required to raise the temperature of a unit mass of that substance by one degree Celsius. In this question, the unknown metal has a specific heat capacity of 0.385. The metal requires 800 joules of heat energy to increase its temperature by 41.6 degrees Celsius. By comparing the given specific heat capacities, we can see that the specific heat capacity of copper is the closest to 0.385. Therefore, the identity of the unknown metal is copper.

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6.

The (+ ve) sign which precedes the Δ H value , indicates that the enthalpy of products is ............ that of reactants

Larger than
Equal
Lower than
Constant

Correct Answer

A. Larger than

Explanation

The positive sign before the ΔH value indicates that the enthalpy of the products is larger than that of the reactants. This means that the reaction is exothermic, releasing heat to the surroundings.

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7.

If the temperature of a substance is doubled , its specific heat will be ..............

Decreased to half
Constant
Increased to double
Increased to four times

Correct Answer

A. Constant

Explanation

When the temperature of a substance is doubled, its specific heat remains constant. Specific heat is defined as the amount of heat energy required to raise the temperature of a substance by a certain amount. It is an intrinsic property of the substance and does not depend on the temperature. Therefore, doubling the temperature does not affect the specific heat of the substance.

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8.

If the two bodies have the same mass , gain the same amount of heat , the raise in the temperature of the second body is double that of the first , therefore the specific heat of the second body is ............ the first one.

Equal to
Double
Half
Quarter

Correct Answer

A. Half

Explanation

If two bodies have the same mass and gain the same amount of heat, but the temperature rise of the second body is double that of the first, it means that the second body requires less heat to increase its temperature compared to the first body. This implies that the specific heat of the second body is half that of the first body.

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9.

In the reaction :

Negative , because the reaction is endothermic
Positive , because the reaction is endothermic
Negative , because the reaction is exothermic
Positive m because the reaction is exothermic

Correct Answer

A. Negative , because the reaction is exothermic

Explanation

The correct answer is "negative, because the reaction is exothermic." In an exothermic reaction, heat is released from the system to the surroundings, resulting in a decrease in the enthalpy of the system. This is represented by a negative sign in the enthalpy change (∆H) of the reaction.

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10.

In the following thermochemical equation : The heat change accompanied with this process is called ............... heat

Formation
Combustion
Dissolving
Neutralization

Correct Answer

A. Dissolving

Explanation

The heat change accompanied with the given thermochemical equation is called "dissolving" heat.

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11.

Anhydrous copper II chloride reacts with water to form hydrous copper II chloride , according to the equation :

-1586 kJ/mol
316 kJ/mol
-110 kJ/mol
-30 kJ/ mol

Correct Answer

A. -30 kJ/ mol

Explanation

The correct answer is -30 kJ/mol. This indicates that the reaction between anhydrous copper II chloride and water is exothermic, releasing energy in the form of heat. The negative sign indicates that the reaction is releasing energy. The value of -30 kJ/mol indicates the amount of energy released per mole of the reactant.

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12.

What is the change in Enthalpy on dissolving 40 g of NaOH in water to form one liter of solution , knowing that the temperature raised by 10.6 C ? .............kJ/mol [ NaOH = 40 g/mol ]

-0.443
-4.4308
-44.308
-443

Correct Answer

A. -44.308

Explanation

When NaOH dissolves in water, it undergoes an exothermic reaction, meaning it releases heat. The change in enthalpy (ΔH) is negative because energy is being released. To calculate the change in enthalpy, we can use the formula ΔH = q/m, where q is the heat released and m is the mass of the substance. In this case, the mass of NaOH is given as 40g/mol and the temperature change is 10.6°C. Since we are dissolving 40g of NaOH in one liter of solution, we can assume the specific heat capacity of water is 4.18 J/g°C. By converting the units and plugging the values into the formula, we find that the change in enthalpy is approximately -44.308 kJ/mol.

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13.

Which of the following remains constant in the closed system ? .......

Energy
Mass
Temperature
Enthalpy

Correct Answer

A. Energy

Explanation

In a closed system, energy remains constant. This is because energy cannot be created or destroyed, it can only be transferred or converted from one form to another. Therefore, the total amount of energy in a closed system remains constant over time.

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14.

Calculate :

15.

Calculate the heat quantity in - kJ - required to raise the temperature of 48.7 g of water from 22.8 C to 62 C

16.

Science Quiz [ Mr, Shokir ]

Which one of the following substances has the higher specific heat ? ...........

Quiz Preview

Using the quantity of heat equation , what would the formula look like if we were calculating the change in temperature ? ........

Dissolving process is called hydration when the solvent is ..........

If the heat content of products is lower than that of reactants , thus the reaction ...........

The (+ ve) sign which precedes the Δ H value , indicates that the enthalpy of products is ............ that of reactants

If the temperature of a substance is doubled , its specific heat will be ..............

If the two bodies have the same mass , gain the same amount of heat , the raise in the temperature of the second body is double that of the first , therefore the specific heat of the second body is ............ the first one.

In the reaction :

In the following thermochemical equation : The heat change accompanied with this process is called ............... heat

Anhydrous copper II chloride reacts with water to form hydrous copper II chloride , according to the equation :

What is the change in Enthalpy on dissolving 40 g of NaOH in water to form one liter of solution , knowing that the temperature raised by 10.6 C ? .............kJ/mol [ NaOH = 40 g/mol ]

Which of the following remains constant in the closed system ? .......

Calculate :

Calculate the heat quantity in - kJ - required to raise the temperature of 48.7 g of water from 22.8 C to 62 C

Calculate the heat quantity in - kJ - required to raise the temperature of 48.7 g of water from 22.8 C to 62 C