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4 years ago

If a helium balloon has a volume of 8.5 L assuming STP conditions, how many moles are there?

Chemistry

1 answer:

LUCKY_DIMON [66]4 years ago

5 0

answer

0.37946 moles

explanation

at STP, there are 22.4 liters for every mole of gas, so divide the number of liters by 22.4 to find the number of moles

number of moles = $8.5 liters * \frac{1 mole}{22.4 liters}$

number of moles = 0.37946 moles

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How mamy moles of NaCl will be produced from 83.0g of Na, assuming Cl2 is available in excess

Anestetic [448]

Answer:

3.62moles

Explanation:

First let us generate a balanced equation for the reaction

2Na + Cl2 —> 2NaCl

Molar Mass of Na = 23g/mol

Mass of Na from the balanced equation = 2 x 23 = 46g

Molar Mass of NaCl = 23 + 35.5 = 58.5g/mol

Mass of NaCl from the balanced equation = 2 x 58.5 = 117g

From the question,

46g of Na produced 117g of NaCl.

Therefore, 83g of Na will produce = (83 x 117)/46 = 211.11g of NaCl

Converting this mass (211.11g of NaCl) to mole, we obtain:

n = Mass /Molar Mass

n = 211.11/ 58.5

3.62moles

8 0

3 years ago

Fe-54 = 5.845%

FrozenT [24]

Answer:

$\boxed {\boxed {\sf 55.76756 \ amu}}$

Explanation:

The average atomic mass is the sum of the product of the given masses and their abundances. We have to complete two steps for each isotope, then add all the products together.

Fe-54

Convert the percent abundance to a decimal by dividing by 100.

5.845/100= 0.05845

Multiply the abundance as a decimal by the mass number. This is the number after the element in the isotope symbol (54 amu).

0.005845 * 54=3.1563 amu

Fe-56

Convert the percent to a decimal.

91.754/100=0.91754

Multiply the decimal by the mass number (56 amu).

0.91754 * 56= 51.38224 amu

Fe-58

Convert the percent to a decimal.

2.119/100=0.02119

Multiply by the mass number (58 amu).

0.02119 * 58 = 1.22902 amu

Average Atomic Mass

Add all the products together to find the average atomic mass.

3.1563 amu + 51.38224 amu + 1.22902 amu =55.76756 amu

The average atomic mass given the percent abundance is 55.7656 atomic mass units.

8 0

3 years ago

Which statement describes a chemical property of oxygen

grin007 [14]

Oxygen can combine with a metal to produce a compound

8 0

3 years ago

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A reaction has a rate constant of 2.08 × 10−4 s−1 at 26 oC and 0.394 s−1 at 79 oC . Determine the activation barrier for the rea

leva [86]

Answer: The activation energy of the reaction is 124.6 kJ/mol

Explanation:

To calculate activation energy of the reaction, we use Arrhenius equation, which is:

$\ln(\frac{K_{79^oC}}{K_{26^oC}})=\frac{E_a}{R}[\frac{1}{T_1}-\frac{1}{T_2}]$

where,

$K_{79^oC}$ = equilibrium constant at 79°C = $0.394s^{-1}$

$K_{26^oC}$ = equilibrium constant at 26°C = $2.08\times 10^{-4}s^{-1}$

$E_a$ = Activation energy of the reaction = ?

R = Gas constant = 8.314 J/mol K

$T_1$ = initial temperature = $26^oC=[26+273]K=299K$

$T_2$ = final temperature = $79^oC=[79+273]K=352K$

Putting values in above equation, we get:

$\ln(\frac{0.394}{2.08\times 10^{-4}})=\frac{E_a}{8.314J/mol.K}[\frac{1}{299}-\frac{1}{352}]\\\\E_a=124595J/mol=124.6kJ/mol$

Hence, the activation energy of the reaction is 124.6 kJ/mol

3 0

3 years ago

A lead mass is heated and placed in a foam cup calorimeter containing 50.0 ml of water at 18.0°c. the water reaches a temperatur

garri49 [273]

Heat gained or loss in a system can be calculated by multiplying the given mass to the specific heat capacity of the substance and the temperature difference. It is expressed as follows:

Heat = mC(T2-T1)

When two objects are in contact, it should be that the heat lost is equal to what is gained by the other. So, the heat released by the lead is equal to the heat that is absorbed by the water.

Heat = mC(T2-T1) = 50.0 mL (1.00 g/mL) (4.18 J/g °C) (20 °C - 18 °C) = 418 J

8 0

4 years ago

Read 2 more answers