What does the number 84 in the name krypton-84 represent

Chemistry

2 answers:

Marysya12 [62]3 years ago

8 0

Mass number ........ ...

inysia [295]3 years ago

7 0

The number ''84'' in the kryton-84 indicates the mass number of this particular isotope, which is the sum of protons and neutrons in the nucleus. It is also approximately equal to the atomic weight of the isotope

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Calcium carbonate is a molecule that contains one atom of calcium, one atom of carbon, and three atoms of oxygen. Which of the f

yuradex [85]

Answer:

CaCO3

Explanation:

From the question we were told that Calcium carbonate contains the following:

Ca = 1atom

C = 1atom

O = 3atoms

Combining the above together we will have: CaCO3

6 0

4 years ago

How many grams of O2 are present in 44.1 L of O2 at STP?

ycow [4]

Taking into accoun the STP conditions and the ideal gas law, the correct answer is option e. 63 grams of O₂ are present in 44.1 L of O2 at STP.

First of all, the STP conditions refer to the standard temperature and pressure, where the values used are: pressure at 1 atmosphere and temperature at 0°C. These values are reference values for gases.

On the other side, the pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:

P×V = n×R×T

where:

P is the gas pressure.
V is the volume that occupies.
T is its temperature.
R is the ideal gas constant. The universal constant of ideal gases R has the same value for all gaseous substances.
n is the number of moles of the gas.

Then, in this case:

P= 1 atm
V= 44.1 L
n= ?
R= 0.082 $\frac{atmL}{molK}$
T= 0°C =273 K

Replacing in the expression for the ideal gas law:

1 atm× 44.1 L= n× 0.082 $\frac{atmL}{molK}$ × 273 K

Solving:

$n=\frac{1 atm x44.1 L}{0.082\frac{atmL}{molK}x273K}$

n=1.97 moles

Being the molar mass of O₂, that is, the mass of one mole of the compound, 32 g/mole, the amount of mass that 1.97 moles contains can be calculated as:

$1.97 molesx\frac{32 g}{1 mole}$ = 63.04 g ≈ 63 g