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Tresset [83]
3 years ago
7

A pure substance containing only one king of ______ .

Chemistry
2 answers:
nadya68 [22]3 years ago
6 0
Atom or element, either one is right.
Lemur [1.5K]3 years ago
5 0
A pure substance containing only one kind of element.
You might be interested in
For a process Arightwards harpoon over leftwards harpoonB, at 25 °C there is 10% of A at equilibrium while at 75 °C, there is 80
Lostsunrise [7]

This question is describing the following chemical reaction at equilibrium:

A\rightleftharpoons B

And provides the relative amounts of both A and B at 25 °C and 75 °C, this means the equilibrium expressions and equilibrium constants can be written as:

K_1=\frac{90\%}{10\%}=9\\\\K_2=\frac{20\%}{80\%}  =0.25

Thus, by recalling the Van't Hoff's equation, we can write:

ln(K_2/K_1)=-\frac{\Delta H}{R}(\frac{1}{T_2} -\frac{1}{T_1} )

Hence, we solve for the enthalpy change as follows:

\Delta H=\frac{-R*ln(K_2/K_1)}{(\frac{1}{T_2} -\frac{1}{T_1} ) }

Finally, we plug in the numbers to obtain:

\Delta H=\frac{-8.314\frac{J}{mol*K} *ln(0.25/9)}{[\frac{1}{(75+273.15)K} -\frac{1}{(25+273.15)K} ] } \\\\\\\Delta H=4,785.1\frac{J}{mol}

Learn more:

  • brainly.com/question/10038290
  • brainly.com/question/19671384
5 0
2 years ago
0.5mol/dm3 hydrochloric acid is added gradually to a flask containing 20cm3 of 2 mol/ dm3 sodium hydroxide solution.
sweet-ann [11.9K]

Answer:

The answer is B which is 40

7 0
2 years ago
Is this example of a direct proportion or an inverse proportion?
ivanzaharov [21]

Answer:

Inverse proportion occurs when one value increases and the other decreases. For example, more workers on a job would reduce the time to complete the task. They are inversely proportional.

6 0
3 years ago
A pure gold ring weighs 23.5 grams. How many atoms of gold<br> are in the ring?
Digiron [165]

The number of atoms of gold in the pure ring are 7.18 × 10²² atoms.

<h3>HOW TO CALCULATE NUMBER OF ATOMS?</h3>

The number of atoms in a substance can be calculated by multiplying the number of moles of the substance by Avogadro's number.

The number of moles in the gold (Au) can be calculated by dividing the mass of gold by its molar mass (196.97g/mol).

no. of moles = 23.5g ÷ 196.97g/mol

no. of moles = 0.119mol

Number of atoms in Au = 0.119 × 6.02 × 10²³

no. of atoms = 7.18 × 10²² atoms.

Therefore, the number of atoms of gold in the pure ring are 7.18 × 10²² atoms.

Learn more about number of atoms at: brainly.com/question/15959704

3 0
2 years ago
Convert 0.900 atm of pressure to its equivalent in millimeters of mercury. express the pressure numerically in millimeters of me
Angelina_Jolie [31]
1 atm = 760 mm Hg

Where 760 mm is the height of Mercury for 1 atm.

For 0.900 atm,

Height of mercury = 0.900*760 = 684 mm Hg
8 0
2 years ago
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