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Len [333]
3 years ago
11

A sample of a compound made entirely from copper and oxygen was found to have a total mass of 0.1431g The mass of the copper In

the compound was found to be 0.1271g. Calculate the number of moles of copper in the sample.
Chemistry
1 answer:
Ket [755]3 years ago
5 0
Number of moles of Cu in 63.546 g is 1 mole

1 / 63.546 = 0.0157366317

Number of moles in 1 g of Cu is 0.0157366317

0.0157366317 x 0.1431

0.002251912 moles will be the answer
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Andrew [12]
The amount of kinetic energy that an object has depends on its mass or how heavy it is and how fast it is moving, or velocity
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18) What is the following number representing: 10m/s West *
ddd [48]

Speed

Explanation:

The distance travelled by a body per unit time

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Sodium metal reacts with water to produce hydrogen gas and sodium hydroxide according to the chemical equation shown below.
UNO [17]

<u>Answer:</u> The enthalpy change of the reaction is -361.6 kJ

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

Moles of sodium = 0.025 moles

Molar mass of sodium = 23 g/mol

Putting values in above equation, we get:

0.025mol=\frac{\text{Mass of sodium}}{23g/mol}\\\\\text{Mass of sodium}=(0.025mol\times 23g/mol)=0.575g

We are given:

Mass of water = 100.00 g

Mass of sodium = 0.575 g

Mass of solution = 100.00 + 0.575 = 100.575 g

To calculate the amount of heat absorbed, we use the equation:

q=m\times C\times \Delta T

where,

q = amount of heat absorbed = ?

m = mass of solution = 100.575 g

C = specific heat capacity of solution = 4.18 J/g°C

\Delta T = change in temperature = (T_2-T_1)=(35.75-25.00)=10.75^oC

Putting all the values in above equation, we get:

q=100.575g\times 4.18J/g^oC\times 10.75^oC=4519.34J=4.52kJ

When heat is absorbed by the solution, this means that heat is getting released by the reaction.

<u>Sign convention of heat:</u>

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

For the given chemical reaction:

2Na(s)+2H_2O(l)\rightarrow NaOH(aq.)+H_2(g)

When 0.025 moles of sodium is reacted, the heat released by the reaction is 4.52 kJ

So, when 2 moles of sodium will react, the heat released by the reaction will be = \frac{4.52}{0.025}\times 2=361.6kJ

Hence, the enthalpy change of the reaction is -361.6 kJ

6 0
3 years ago
Which of the following is a physical property? A. Flammability B. Heat of combustion C. Solubility D.Toxicity
Rasek [7]

I think it would be solubility but I’m not sure

6 0
3 years ago
Read 2 more answers
Identify each statement as true or false. Explain in every case.a.Ionization energies are always negative quantities.b.Oxygen ha
worty [1.4K]

Answer:

(a) FALSE

(b) FALSE

(c) TRUE

(d) FALSE

Explanation:

Ionization energy refers to the energy needed for removal of a valence electron present in valence shell of a gaseous atom.

(a) <u>The value of ionization energy of an atom is always</u><u> positive</u>. This is because energy has to be always supplied or provided to a gaseous atom for the removal of the valence electron.

<em><u>Therefore, the statement (A) is</u></em><em><u> false</u></em>

   

(b) The ionization energy of an atom <u>increases across a period</u> i.e. from left to right. This is because the <u>effective nuclear charge that is experienced by the valence electron increases</u> from left to right in the periodic table, as the atomic number increases.

So, more energy is required to remove the valence electron of fluorine as compared to oxygen.

<u>Therefore, the </u><u>ionization energy of fluorine is greater than oxygen</u><u>.</u>

<em><u>Therefore, the statement (B) is</u></em><em><u> false</u></em>

(c) <u>First ionization energy</u> is energy needed for removal of first electron present in valence shell of a neutral atom. Whereas, <u>second ionization energy</u> is the energy needed for removal of second electron present in valence shell of a monovalent cation

The second ionization energy of an atom is always greater than the first ionization energy. This is because removing<u> an electron from a positively charged species, requires more energy.</u>

<em><u>Therefore, the statement (C) is</u></em><em><u> true</u></em>

<em><u /></em>

(d) <u>The third ionization energy </u>refers to the energy needed to remove the third electron from a divalent cation.

<em><u>Therefore, the statement (D) is</u></em><em><u> false</u></em>

7 0
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