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Olenka [21]
3 years ago
5

Which of the following measurements is used to measure the enthalpy of combustion? A. None of these B. Measuring the change in t

emperature when two liquids are mixed. C. It cannot be measured, only calculated using the equation: q = mc∆T. D. Measuring the change in temperature of a beaker of water.
Chemistry
1 answer:
DaniilM [7]3 years ago
4 0

Answer: Option (C) is the correct answer.

Explanation:

In a substance, the total energy of its molecular motion is known as heat. Whereas when we measure the average energy of molecular motion of a substance then it is known as temperature.

So, any increase or decrease in temperature will lead to change in heat of a substance.

When one mole of a substance is burned then the amount of energy released  in the form of heat is known as heat of combustion.

Relation between heat and temperature is as follows.

                    q = m \times C \times \Delta T

Thus, we can conclude that to measure the enthalpy of combustion it cannot be measured, only calculated using the equation; q = mc \Delta T.

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Hi, May I have Chem help please? Please Keep the answer as simple as possible.
lesya [120]

Explanation:

a positively charged nucleus is surrounded by mostly empty space.

4 0
3 years ago
How many moles are in 2.12g Cr2O3
ohaa [14]

Answer:

0.01395mol Cr2O3

Explanation:

the molar mass of Cr2O3 is 151.9904 g/mol

2.12g Cr2O3 x 1 mol/151.9904g = 0.01395mol Cr2O3

4 0
3 years ago
The ka of acetic acid ch3co2h is 1.8 x10-5. what is the ph
AysviL [449]
You must know the concentration of the acetic acid. Suppose the concentration is 0.1 M. The solution is as follows:

            CH₃COOH → CH₃COO⁻ + H⁺
 I                  0.1               0              0
C                 -x                +x            +x
E              0.1 - x             x               x

Ka = (x)(x)/(0.1 - x)
1.8×10⁻⁵ = x²/(0.1 - x)
Solving for x,
x = 1.333×10⁻³ = H⁺

pH = -log[H⁺] = -log(1.333×10⁻³)
pH = 2.88

6 0
3 years ago
a factor of 8, it means that A is now only 1/8 of its original concentration. A first order reaction, where A → products, has a
Trava [24]

Answer:

It takes 1.32x10⁻⁷s for the concentration of A to fall by a factor of 8

Explanation:

The equation that represents a first-order kinetics is:

Ln ([A] / [A]₀] = -kt

<em>Where [A] is actual concentration, [A]₀ is initial concentration, K is rate constant (For the given problem, 1.57x10⁷s⁻¹ and t is time.</em>

<em />

As you want the time when you have [A] in a factor of 8 = [A] / [A]₀ = 1/8

Replacing:

Ln ([A] / [A]₀] = -kt

Ln (1/8) = -1.57x10⁷s⁻¹*t

t = 1.32x10⁻⁷s

<h3>It takes 1.32x10⁻⁷s for the concentration of A to fall by a factor of 8</h3>

4 0
3 years ago
How do metals form chemical bonds with other metals?
gogolik [260]

Answer:

Metallic bonding  

Explanation:

Metals have low ionization energies. Therefore, their valence electrons are easily delocalized (attracted to the neighbouring metal atoms). These delocalized electrons are then not associated with a specific metal atom.  Since the electrons are “free”, the metal atoms have become cations, and the electrons are free to move throughout the whole crystalline structure.

We say that a metal consists of an array of cations immersed in a sea of electrons .

The electrons act as a “glue” holding the cations together.

Metallic bonds are the attractive forces between the metal cations and the sea of electrons.

In an NaK alloy, for example, the Na and K atoms contribute their valence electrons to the "sea".  The atoms aren’t bonded to each other, but they are held in place by the metallic bonding.

4 0
3 years ago
Read 2 more answers
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