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3 years ago

For question #12, use the following picture: 12. What element is this? How do you know?

Chemistry

2 answers:

labwork [276]3 years ago

8 0

Answer: The element shown in the image is Helium (He).

Explanation: We are given a image of an atom having protons, neutrons and electrons.

Number of protons as shown in image = 2

Number of neutrons as shown in image = 2

Number of electron as shown in image = 2

Atomic number = Number of protons = Number of electrons

Atomic number of the element = 2

Atomic Mass = Number of protons + Number of neutrons

Atomic mass = 2 + 2 = 4

The element having Atomic number = 2 and mass number = 4 is Helium.

Element = $^4_2\textrm{He}$

morpeh [17]3 years ago

3 0

I believe the element is Helium. I know this because an atom of helium has an atomic number of 2, meaning it has 2 protons. Because it is an atom of helium and not an ion of helium it also possess the same number of electrons as well which is 2.

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3 years ago

What is the empirical formula of a compound containing 5.03 grams carbon, 0.42 grams hydrogen, and 44.5 grams chlorine?

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Answer:

The right choice is CHCl₃

Explanation:

To find the empirical formula firstly, change the mass to moles.

For Carbon :

no. of moles = (mass / molar mass) = (5.03 g / 12 g/mol )= 0.42 mol

For Hydrogen :

no. of moles = (mass / molar mass) = (0.42 g / 1 g/mol )= 0.42 mol

For Chlorine :

no. of moles = (mass / molar mass) = (44.5 g / 35.5 g/mol )= 1.25 mol

The ratio for Carbon and Hydrogen is 1 : 1

0.42 mol / 042 mol =1.00

Then find a ratio between the moles.

The ratio of Chlorine to both Carbon and Hydrogen is 3:1

1.25 mol / 0.42 mol = 2.98 ≅ 3

So the ratio is 1 C : 1 H : 3 Cl.

So, the right choice is CHCl₃

Carbon usually forms four bonds one to Hydrogen and 3 to Chlorine atoms.

Chlorine usually forms one bond to Carbon atom.

Hydrogen usually forms one bond Carbon atom.

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3 years ago

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3 years ago

Zns (zinc sulfide) (Zn = 65.38; S = 32.06] *

irakobra [83]

The question is incomplete, the complete question is;

Zinc and sulfur react to form zinc sulfide by the equation shown below. How many grams of ZnS can be formed when 12.0 g of Zn reacts with 6.50 g of S? (Atomic mass: Zn = 65.38, S = 32.06).

Answer:

17.5 g of ZNS

Explanation:

The equation of the reaction is;

Zn(s) + S(s) ------->ZnS(s)

Number of moles of Zn = 12.0/65.38 = 0.18 moles

Number of moles of S = 6.50/32.06 = 0.20 moles

Hence Zn is the limiting reactant

If 1 mole of Zn yields 1 mole of ZnS

Then 0.18 moles of Zn also yields 0.18 moles of ZnS

Mass of ZnS produced = 0.18 moles * 97.44 g/mol = 17.5 g of ZNS

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3 years ago