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3 years ago

Why did Mendeleev leave gaps

1 answer:

7 0

Mendeleev left gaps in the periodic table because, in the future, he knew that there would be more elements to be discovered because not all elements were discovered at the time.

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The producer in an energy pyramid contains about 1,000 kcal of energy

xz_007 [3.2K]

The corrects answer is 900 kcals

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3 years ago

Please help 10 points asap

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Answer:

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Which statement is true of a heterogeneous mixture but not of a

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Answer:

Explanation:

well heterogenous mixtures are not uniformly distributed these meaning whatever components are "mixed" can be seperated easily

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while Homogeneous mixture cannot be seen seperated

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3 years ago

Which will not appear in the equilibrium constant expression for the reaction below?

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is the answer i just took the tes

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When 1.045 g of CaO is added to 50.0 mL of water at 25.0 °C in a calorimeter, the temperature of the water increases to 32.3 °C.

Rus_ich [418]

Answer:

1.71 kJ/mol

Explanation:

The expression for the calculation of the enthalpy change of a process is shown below as:-

$\Delta H=m\times C\times \Delta T$

Where,

$\Delta H$ is the enthalpy change

m is the mass

C is the specific heat capacity

$\Delta T$ is the temperature change

Thus, given that:-

Mass of CaO = 1.045 g

Specific heat = 4.18 J/g°C

$\Delta T=32.3-25.0\ ^0C=7.3\ ^0C$

So,

$\Delta H=1.045\times 4.18\times 7.3\ J=31.88713\ J$

Also, 1 J = 0.001 kJ

So,

$\Delta H=0.03189\ kJ$

Also, Molar mass of CaO = 56.0774 g/mol

$Moles=\frac{Mass}{Molar\ mass}=\frac{1.045}{56.0774}\ mol=0.01863\ mol$

Thus, Enthalpy change in kJ/mol is:-

$\Delta H=\frac{0.03189}{0.01863}\ kJ/mol=1.71\ kJ/mol$

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3 years ago