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2 years ago

7

If the oxidation number of nitrogen in a certain molecule changes from +3 to -2 during a reaction, is the nitrogen oxidized or r

educed? how many electrons are gained or lost by the nitrogen atom?

1 answer:

aliina [53]2 years ago

7 0

The nitrogen has been reduced or has undergone reduction and it has gained one electron

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Which of the following is a balanced equation?<br><br>Select one:<br>a. A<br>b. B<br>c. C<br>d. D

Phantasy [73]

Answer:

B

Explanation:

Balanced equations have the same number of elements on both sides. If the number of elements are equal to each other for every element in the equation on both sides, then the equation is balanced.

Important concept : The big number before an element or compound represents how many molecules of that compound or element there are in a reaction. To find the number of atoms of each element you multiply the coefficient by the subscript ( small number ) which represents the number of atoms of that element in each molecule. Ex. 3H2O. There is a coefficient of 3 meaning that there are 3 molecules of H2O. There is a subscript after H meaning there are 2 atoms of hydrogen in each molecule. To find the total number of atoms we multiply the subscript of hydrogen by the coefficient of the whole molecule. 3 * 2 = 6 , so there are a total of 6 atoms of hydrogen in 3H2O

A) Cu + 2AgNO3 ==> CuNO3 + 2Ag

1 Cu 1

2 Ag 2

2 N 1

3 O 3

The amount of nitrogen atoms is different on both sides of the equation therefore this is not a balanced equation

B) CCl4 + O2 ==> CO2 + 2Cl2

1 C 1

4 Cl 4

2 O 2

The number of atoms of each element is the same on both sides of the equation therefore this is the balanced equation, however lets check the other answer choices just in case.

C) 2K + H2SO4 ==> K2SO4 + 2H2

2 K 2

1 H 4

1 S 1

4 O 4

The number of Hydrogen atoms are different on each side of the equation therefore this is not a balanced equation.

D) 2Al2O3 ==> 2Al + 3O2

4 Al 2

6 O 6
There are a different amount of aluminum atoms on both sides of the equation therefore this is not a balanced equation.

3 0

2 years ago

I have 2 samples of solid chalk (aka calcium carbonate). Sample A has a total mass of 4.12 g and Sample B has a total mass of 19

IRINA_888 [86]

Answer:

A) Sample B has more calcium carbonate molecules

Explanation:

M = Molar mass of calcium carbonate = 100.0869 g/mol

$N_A$ = Avogadro's number = $6.022\times 10^{23}\ \text{mol}^{-1}$

For the 4.12 g sample

Moles of a substance is given by

$n=\dfrac{m}{M}\\\Rightarrow n=\dfrac{4.12}{100.0869}\\\Rightarrow n=0.0411\ \text{mol}$

Number of molecules is given by

$nN_A=0.0411\times 6.022\times 10^{23}=2.48\times 10^{22}\ \text{molecules}$

For the 19.37 g sample

$n=\dfrac{19.37}{100.0869}\\\Rightarrow n=0.193\ \text{mol}$

Number of molecules is given by

$nN_A=0.193\times 6.022\times 10^{23}=1.16\times 10^{23}\ \text{molecules}$

$1.16\times 10^{23}\ \text{molecules}>2.48\times 10^{22}\ \text{molecules}$

So, sample B has more calcium carbonate molecules.

The ratio of the elements of carbon, oxygen, calcium atoms, ions, has to be same in both the samples otherwise the samples cannot be considered as calcium carbonate. Same is applicable for impurities. If there are impurites then the sample cannot be considered as calcium carbonate.

7 0

3 years ago

What is the volume of 0.640 grams of Oz gas at Standard Temperature and Pressure (STP)?

Ilia_Sergeevich [38]

Answer: The volume of 0.640 grams of $O_{2}$ gas at Standard Temperature and Pressure (STP) is 0.449 L.

Explanation:

Given: Mass of $O_{2}$ gas = 0.640 g

Pressure = 1.0 atm

Temperature = 273 K

As number of moles is the mass of substance divided by its molar mass.

So, moles of $O_{2}$ (molar mass = 32.0 g/mol) is as follows.

$No. of moles = \frac{mass}{molar mass}\\= \frac{0.640 g}{32.0 g/mol}\\= 0.02 mol$

Now, ideal gas equation is used to calculate the volume as follows.

PV = nRT

where,

P = pressure

V = volume

n = no. of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

$PV = nRT\\1.0 atm \times V = 0.02 mol \times 0.0821 L atm/mol K \times 273 K\\V = 0.449 L$

Thus, we can conclude that the volume of 0.640 grams of $O_{2}$ gas at Standard Temperature and Pressure (STP) is 0.449 L.

6 0

3 years ago

In which case would an electron experience the greatest effective nuclear charge? not all cases describe an atom in the ground s

lisabon 2012 [21]

One electron in an atom experiences the entire positive charge of the nucleus. Coulomb's law can be used in this situation to determine the effective nuclear charge.

In contrast, the outside electrons in an atom with many electrons are drawn to the positive nucleus and repelled by the negatively charged electrons at the same time. The force between two stationary, electrically charged particles can be measured using Coulomb's law inverse-square law, also known as Coulomb's law. Conventionally, the electric force between two charged objects at rest is referred to as the Coulomb force or electrostatic force.

The electron is a subatomic particle with the symbol e or with an electric charge of one elementarily negative charge. The lepton particle family's first generation includes electrons.

Learn more about Coulomb's law here

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5 0

1 year ago

Does H₂O have a subscript?

erma4kov [3.2K]

<span> 2 hydrogen atoms attached to an oxygen atom.</span>

7 0

2 years ago

Read 2 more answers