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2 years ago

What is the empirical formula for a substance that contains 24.59% phosphorus and 75.41% fluorine by mass?

1 answer:

8 0

In order to obtain the empirical formula, first divide each element by its molar mass which can be found in the periodic table. The answer in the first step would be the number of moles of each element. Then divide each element with the lowest number of moles obtained in the first step in this case Phosphorus had the lowest number of moles. Then round it up to the nearest whole number. The empirical formula then is Phosphorus pentafluoride or PF5.

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Nitrogen has an average atomic mass of 14.00674. it has two isotopes, n-14 and n-15, with atomic masses of 14.0031 amu and 15.00

masya89 [10]

In this case, we are going to assume that there are 100 atoms to make things easier.

Let R% be the abundance of n-15. With this in mind, we calculate the abundance of n-14 to be 100%-R%

14.0031*(100-R)% + 15.001 * R%= 14.00674
In this case, we can delete or ignore the % sign since we do not want to carry it around, however, we need to keep in mind that the final answer is in %

14.0031*(100-R) + 15.001 * R= 14.00674
1400.31-14.0031R+15.001R=1400.674
0.9979R=0.364
R=0.3648

Then, the abundance of n-15 is 0.3648%

5 0

2 years ago

A strip of sodium metal is bombarded by violet light (wavelength = 410 nm) at a rate of 10,000 photons per second, which causes

Zarrin [17]

Answer:

The minimum energy required to eject an electron from sodium will be bigger.

Explanation:

red light has a higher wavelength, that mean that the energy that emitted is lower in comparison with the violet light.

If the rate of the photons is the same, 10,000 photons per second, that means that the required energy to take an electron need to be bigger to have the same effect.

Hope this info is useful.

3 0

3 years ago

Read 2 more answers

Magnesium metal burns in air to form a mixture of magnesium oxide (MgO, M = 40.31) and magnesium nitride (Mg3N2, M = 100.95). A

dedylja [7]

Answer:

26.95 %

Explanation:

Air contains the highest percentage of oxygen and nitrogen gases. Magnesium then combines with both of the gases:

$2 Mg (s) + O_2 (g)\rightarrow 2 MgO (s)$

$3 Mg (s) + N_2 (g)\rightarrow Mg_3N_2 (s)$

Firstly, find the total number of moles of magnesium metal:

$n_{Mg} = \frac{1.000 g}{24.305 g/mol} = 0.041144 mol$

Let's say that x mol react in the first reaction and y mol react in the second reaction. This means:

$x + y = 0.041144 mol$

According to stoichiometry, we form:

$n_{MgO} = x mol, n_{Mg_3N_2} = \frac{y}{3} mol$

Multiplying moles by the molar mass of each substance will yield mass. This means we form a total of:

$m_{MgO} = 40.31x g, m_{Mg_3N_2} = \frac{y}{3} 100.95 g =$

The total mass is given, so we have our second equation to solve:

$40.31x + 33.65y = 1.584$

We have two unknowns and two equations, we may then solve:

$x + y = 0.041144$

$40.31x + 33.65y = 1.584$

Express y from the first equation:

$y = 0.041144 - x$

Substitute into the second equation:

$40.31x + 33.65(0.04144 - x) = 1.584$

$40.31x + 1.39446 - 33.65x = 1.584$

$6.66x = 0.18954$

$x = 0.028459$

$y = 0.041144 - x = 0.012685$

Moles of nitride formed:

$n_{Mg_3N_2} = \frac{y}{3} = 0.0042282 mol$

Convert this to mass:

$m_{Mg_3N_2} = 0.0042282 mol\cdot 100.95 g/mol = 0.4268 g$

Find the percentage:

$\omega_{Mg_3N_2} = \frac{0.4268 g}{1.584 g}\cdot 100\% = 26.95 \%$

7 0

2 years ago

lava is a hot liquid rock. when lava flows over solid ground beneath it increases in temperature. what happens to the molecules

MatroZZZ [7]

Answer:

Lava is hot liquid rock. When lava flows over solid ground, the solid ground beneath it increases in temperature. What happens to the molecules in the solid ground when the temperature is increasing? The energy of the molecules in the ground decreases.

7 0

2 years ago

Look at 3 or 4 other atoms using the simulation. Do any of them ahve a whole number for atomic mass?

In-s [12.5K]

Answer:

There are three isotopes of silicons. They have masses numbers of 28, 29 and 30. The average amount of silicons is 28.086alum

Explanation:

I learned this in class three days ago so I hope this is helpful i'm in high school ask me for help when ever you want Iĺl help you

7 0

2 years ago