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Anton [14]
2 years ago
7

A scientist has a container with a substance inside. At first, the molecules in the substance move away from each other. Later,

the
molecules move around each other
What change did the scientist observe in the substance?
A. Before, the substance was a liquid. Later, it was a solld.
B. Before, the substance was a gas, Later, it was a liquid
ООО
C. Before, the substance was a liquid. Later, it was a gas.
D. Before, the substance was
solid. Later, it was a liquid
Chemistry
1 answer:
ArbitrLikvidat [17]2 years ago
7 0
The answers here is B) Before, the substance was a gas, later it was a liquid.

Gas particles move freely and away from each other. However, liquid particles move around each other.

Hope this helps! :)(
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Write a net ionic equation for the reaction that occurs when nickel(ii carbonate and excess hydrobromic acid (aq are combined.
seropon [69]
First, we write the reaction equation:
NiCO₃ + 2HBr → NiBr₂ + H₂CO₃

Now, writing this in ionic form:
NiCO₃ + 2H⁺ + 2Br⁻ → NiBr₂ + 2H⁺ + CO₃⁻²

(NiCO₃ is insoluble so it does not dissociate in to ions very readily)

Overall equation:
NiCO₃ + 2Br⁻ → NiBr₂ + CO₃⁻²
7 0
2 years ago
Using the following thermochemical equation, determine the amount of heat produced from the combustion of 24.3 g benzene (C6H6).
Anna007 [38]

Answer:

ΔH = -976.5 kJ

Explanation:

For the reaction given, there are 2 moles of benzene (C6H6). The heat of this reaction is -6278 kJ, which means that the combustion of 2 moles of benzene will lose 6278 kJ of heat. It is an exothermic reaction.

The value of ΔH, the enthalpy, is a way of measurement of the heat, and it depends on the quantity of the matter (number of moles).

So, 24.3 g of benzene has :

n = mass/ molar mass

n = 24.3/78.11

n = 0.311 moles

2 moles ------------ -6278 kJ

0.311 moles ----------- x

By a simple direct three rule:

2x = -1953.08

x = -976.5 kJ

3 0
2 years ago
Your friend says, “chemical changes are caused by an input in energy. In physical changes, there is no transfer of energy” is yo
Viktor [21]

Answer: Your friend is incorrect.

Explanation: If we have an object or something that isn’t moving, (let’s say a notebook on a desk). If there is change, and the notebook moves, there is acceleration. Force = Mass times acceleration, f = m*a. There has to be a force, first of all. If you touched the notebook and moved it, some of your energy is transferred and now the notebook has kinetic energy. If our system is you and the notebook, the total energy doesn’t change. the energy is transferred, but doesn’t change. Your friend is not correct. Please give brainliest hope this helped!

6 0
2 years ago
To determine the enthalpy and entropy of dissolving a compound, you need to measure the Ksp at multiple _______. Then, plot ln(K
Aloiza [94]

Answer:

To determine the enthalpy and entropy of dissolving a compound, you need to measure the Ksp at multiple temperatures. Then, plot ln(Ksp) vs. 1/T. The slope of the plotted line relates to the enthalpy (ΔH) of dissolving and the intercept of the plotted line relates to the entropy (ΔS) of dissolving.

Explanation:

Hello there!

In this case, according to the given information, it turns out possible for us use the thermodynamic definition of the Gibbs free energy and its relationship with Ksp as follows:

\Delta G=-RTln(Ksp)\\\\\Delta G=\Delta H-T\Delta S

Thus, by combining them, we obtain:

-RTln(Ksp)=\Delta H-T\Delta S\\\\ln(Ksp)=-\frac{\Delta H}{RT} +\frac{T\Delta S}{RT} \\\\ln(Ksp)=-\frac{\Delta H}{RT} +\frac{\Delta S}{R}

Which is related to the general line equation:

y=mx+b

Whereas:

y=ln(Ksp)\\\\m=-\frac{\Delta H}{R} \\\\x=\frac{1}{T} \\\\b=\frac{\Delta S}{R}

It means that we answer to the blanks as follows:

To determine the enthalpy and entropy of dissolving a compound, you need to measure the Ksp at multiple temperatures. Then, plot ln(Ksp) vs. 1/T. The slope of the plotted line relates to the enthalpy (ΔH) of dissolving and the intercept of the plotted line relates to the entropy (ΔS) of dissolving.

Regards!

8 0
2 years ago
Which of these statements is not necessarily true for two objects in thermal equilibrium?
Dmitrij [34]

1. Answer: C. The objects' temperatures have both changed by the same amount.

Explanation:

An object is said to be in thermal equilibrium when the objects have attained same temperature. Heat transfer from hotter object to colder one in contact takes place until the temperature of the two are equal. It is not necessary that the temperature of both the objects changes by same amount. After attainment of thermal equilibrium, the temperature of the objects stop changing and the tiny particles of the object move at the same rate.

Hence, the objects' temperatures have both changed by the same amount. is not necessarily true for two objects in thermal equilibrium.

2. Answer: C. Objects are made of tiny particles, and their motion depends on the temperature.

Explanation:

Kinetic theory of heat states that the kinetic energy of constituent particles determine the temperature of the object. The statement that best explains this is Objects are made of tiny particles, and their motion depends on the temperature.

5 0
2 years ago
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