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2 years ago

What does the number 18.9984 represent in the image?

Chemistry

1 answer:

Yanka [14]2 years ago

4 0

The element symbol in chemistry comprises atomic number and mass number.

Atomic number is written on the top of element and mass number is written at the bottom.

For eg:

If Y is an element that is having atomic number a and mass number x. Then its denotion will be:

ᵃYₓ.

So here ⁹F₁₈.₉₉

Here 18.99 will denote mass number while 9 will denote atomic number.

You might be interested in

The electron configurations of some elements are given. Based on the electron configurations, which elements can likely form ion

sergeinik [125]

In the case of Zn, it is likely eligible for one charge, as its 3d is full, it can lose the electrons from the 4s2 level that it does to become Zn2+.

Iron has 6 electrons in the 3d energy level, which signifies that it would give up 6+2 to get to the next stable energy level. It is much convenient for it to give up the 4s2 and then one more out of the 3d6 to produce Fe2+ and Fe3+ respectively.

Sodium has one electron to give away in the 3s energy level, as soon as it gives its one electron, it will look like Ne. In silver, the 4d10 energy level is full, it can only give up the 5s1 electron easily.

In the case of cobalt, the electrons can be taken from the 4s2 energy level and then one more out of the 3d7 energy level, and after that more and more again. Thus, it can go from +5 to -1 charge, due to much more happening in the 3d7 energy level.

Therefore, cobalt can likely form ions with multiple charges.

7 0

3 years ago

Box 1

Alex73 [517]

10g

Explanation:

Box 1, Mass of A = 10g

Box 2, Mass of B = 5g

Box 3, = 1A + 1B

Unknown:

Mass of B that would combine with mass of 20g of A

Solution:

Mass ratio of A to B:

$\frac{mass of A}{mass of B}$ = mass ratio

$\frac{10}{5}$ = mass ratio

The mass ratio of A to B = 2: 1

Now, number of B that will combine with 20g of A;

$\frac{mass of A}{mass of B}$ = mass ratio

$\frac{20}{mass of B}$ = $\frac{2}{1}$

Mass of B = 10g

10g of B would combine with 20g of A

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7 0

3 years ago

Read 2 more answers

How many grams of Fe3O4 are required to react completely with 300 grams of H2?

vekshin1

Answer:

2023.04 g

Explanation:

Magnetite reacts with hydrogen to produce Iron metal and steam. Steam instead of water is produced as the reaction occurs at temperatures above the boiling point of water.

Fe₃O₄ + 4 H₂ → 3 Fe +4 H₂O

From the equation, 1 mole of Fe₃O₄ reacts with 4 moles of H₂.

69.76 grams of H₂ has the following number of moles.

Number of moles= mass/RAM

=69.76/2

=34.88 moles.

The reaction ratio of Fe₃O₄ to H₂ is 1:4

Thus number of moles of magnetite= (1×34.88)/4

=8.72 moles.

Mass= moles × molecular weight

=8.72 moles × (56×3+16×4)

=2023.04 grams

8 0

3 years ago

How many liters of hydrogen are needed to produce 34 grams NH3

polet [3.4K]

You would need 1000 liters

8 0

2 years ago

A 200.0mL closed flask contains 2.000mol of carbon monoxide gas and 2.000mol of oxygen gas at the temperature of 300.0K. How man

max2010maxim [7]

Answer:

There will react 0.400 moles of oxygen.

Explanation:

Step 1: Data given

Volume of the closed flask = 200.00 mL = 0.2 L

Number of moles of CO = 2.000 mol

Number of moles of O2 = 2.000 mol

Temperature = 300.0 K

Pressure decreases with 10%

Step 2: The balanced equation

2CO(g)+O2(g)⟶2CO2(g)

Step 3: Calculate the initial pressure of the flask before the reaction

P = nRT/V

⇒ with n = the number of moles (2.000 moles CO + 2.000 moles O2 = 4.000 moles)

⇒ R is gas constant (0.08206 atm*L/mol*K)

⇒T = the temperature = 300.0K

⇒ V = the volume = 200.0 mL = 0.2 L

P = (4 * 0.08206*300)/0.2

P = 492.36 atm

Step 4: When the pressure is 10 % decreased:

The final pressure = 492.36 - 49.236 = 443.124 atm

Step 5: Calculate the number of moles

n = PV/RT

⇒ with n = the number of moles

⇒ with P = the pressure = 443.124 atm

⇒ V = the volume = 200.0 mL = 0.2 L

⇒ R is gas constant (0.08206 atm*L/mol*K)

⇒T = the temperature = 300.0K

n =(443.124*0.2)/(0.08206*300)

n = 3.6 moles = total number of moles

Step 6: Calculate number of moles

For the reaction :2CO(g) + O₂(g) ⟶ 2CO₂(g)

For each mole of O2 we have 2 moles of CO, to produce 2 moles of CO2

Moles CO = (2 -2X) moles

Moles O2 = (2-X) moles

Moles CO2 = 2X

The total number of moles (4 -X)= 3.6 moles

Where X are moles that react

X = 0.400 moles

There will react 0.400 moles of oxygen.

6 0

3 years ago