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Vinil7 [7]
4 years ago
7

What does the number below each element's symbol represent?

Chemistry
2 answers:
storchak [24]4 years ago
8 0

The answer to the question is B

marissa [1.9K]4 years ago
4 0

Answer:

B. The average atomic mass.

<em>APEX</em>

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What 3 variables were changed in the pendulum experiment?
Paraphin [41]

Answer:

In this experiment, the period of the pendulum is the dependent variable. There are three independent variables: the pendulum mass, the amplitude of the swing, and the length of the pendulum string.

Explanation:

5 0
3 years ago
Sulfur dioxide, SO 2 ( g ) , can react with oxygen to produce sulfur trioxide, SO 3 ( g ) , by the reaction 2 SO 2 ( g ) + O 2 (
aleksley [76]

<u>Answer:</u> The amount of heat produced by the reaction is -21.36 kJ

<u>Explanation:</u>

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles.

The equation used to calculate enthalpy change is of a reaction is:

\Delta H^o_{rxn}=\sum [n\times \Delta H_f_{(product)}]-\sum [n\times \Delta H_f_{(reactant)}]

For the given chemical reaction:

2SO_2(g)+O_2(g)\rightarrow 2SO_3(g)

The equation for the enthalpy change of the above reaction is:

\Delta H_{rxn}=[(2\times \Delta H_f_{(SO_3(g))})]-[(2\times \Delta H_f_{(SO_2(g))})+(1\times \Delta H_f_{(O_2(g))})]

We are given:

\Delta H_f_{(SO_2(g))}=-296.8kJ/mol\\\Delta H_f_{(SO_3(g))}=-395.7kJ/mol\\\Delta H_f_{(O_2(g))}=0kJ/mol

Putting values in above equation, we get:

\Delta H_{rxn}=[(2\times (-395.7))]-[(2\times (-296.8))+(1\times (0))]\\\\\Delta H_{rxn}=-197.8kJ/mol

To calculate the number of moles, we use ideal gas equation, which is:

PV=nRT

where,

P = pressure of the gas = 1.00 bar

V = Volume of the gas = 2.67 L

n = number of moles of gas = ?

R = Gas constant = 0.0831\text{ L. bar }mol^{-1}K^{-1}

T = temperature of the mixture = 25^oC=[25+273]K=298K

Putting values in above equation, we get:

1.00bar\times 2.67L=n\times 0.0831\text{ L. bar }mol^{-1}K^{-1}\times 298K\\\\n=\frac{1\times 2.67}{0.0831\times 298}=0.108mol

To calculate the heat released of the reaction, we use the equation:

\Delta H_{rxn}=\frac{q}{n}

where,

q = amount of heat released = ?

n = number of moles = 0.108 moles

\Delta H_{rxn} = enthalpy change of the reaction = -197.8 kJ/mol

Putting values in above equation, we get:

-197.8kJ/mol=\frac{q}{0.108mol}\\\\q=(-197.8kJ/mol\times 0.108mol)=-21.36kJ

Hence, the amount of heat produced by the reaction is -21.36 kJ

3 0
3 years ago
What pressure is requred to contain 0.023 moles of nitrogen gas in a 4.2 L container at a
zubka84 [21]

Answer:

0.13 atm

Explanation:

Using the Ideal Gas Law; PV=nRT, we can rearrange to solve for pressure.

P=nRT/V

P is pressure, n is number of moles (0.023), R is a constant (0.08206 L*atm/mol*K), T is temperature in Kelvin (293.15K) and V is volume, 4.2 L.

So, plugging in;

P=(0.023mol)(0.08206L*atm/mol*K)(293.15K)/(4.2 L)

P=0.1317 atm

P=0.13 atm; multiply by 760 to get to Torr or mmHg.

5 0
2 years ago
6. The random motion of the particle in a substance is greatest when the<br>substance is​
fredd [130]

Answer:

when the substance is decrease

Explanation:

3 0
3 years ago
How many moles of propane
cupoosta [38]
Starting mass: 294
Mass ratio: 3/5
6 0
2 years ago
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