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Nataly [62]
2 years ago
9

Magnesium has three stable isotopes. One has 12 neutrons the second has 13 and the third has 14. Which one is the most abundant?

How do you know?
Chemistry
1 answer:
fiasKO [112]2 years ago
7 0

Answer:

12

Explanation:

If you look at the periodic table, you can see that magnesium has an atomic mass of 24.305.  Subtract the number of protons from this to get neutrons.

24.305 - 12 = 12.305

12.305 is the average amount of neutrons a magnesium atom can have.  A magnesium atom can have 12, 13, or 14 neutrons.  The average, based on the natural abundance, is 12.305.  To find which isotope is more abundant, you need to pick the number that is closest to the average.  This would make the most abundant isotope the one with 12 neutrons.

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100 PIONTSSSSS HELP ASAP
valina [46]

Left Panel

Short answer A

<em><u>Solution</u></em>

Since you have been given choices, my sloppy numbers will do, but it anyone is going to see this, YOU SHOULD CLEAN  THEM UP WITH THE NUMBERS THAT COME FROM YOUR PERIODIC TABLE.

Equation

Sodium Phosphate + Calcium Chloride ===> Sodium Chloride + Calcium Phosphate.

Na3PO4 + CaCl2 ===> NaCl + Ca3(PO4)2

<em><u>Step One</u></em>

Balance the Equation

2Na2PO4 + 3CaCl2 ==> 6NaCl + Ca3(PO4)2

<em><u>Step Two</u></em>

Find the molar mass of CaCl2

Ca = 40

2Cl = 71

Molar Mass = 40 + 71 = 111 grams/mole

<em><u>Step Three</u></em>

Find the number of moles of CaCl2

Given mass = 379.4

Molar Mass = 111

moles = given Mass / molar Mass

moles of CaCl2 = 379.4/111 = 3.418 moles

<em><u>Step Four</u></em>

Find the number of moles of Ca3(PO4)2 needed.

This requires that you use the balance numbers from the balanced equation.

For every 3 moles of CaCl2 you have, you get 1 mole of Ca3(PO4)2

n_moles of Ca3(PO4)2 = 3.418 / 3 = 1.13933 moles

<em><u>Step Five</u></em>

Find the molar mass of Ca3(PO4)2

From the periodic table,

3Ca = 3 * 40 = 120

2 P  = 2 * 31 =    62

8 O = 8 * 16   =128

Molar Mass = 120 + 62 + 128= 310 grams per mole.

<em><u>Step Six</u></em>

1 mole of Ca3(PO4)2 has a molar mass of 310 gram

1.13933 moles of Ca3(PO4)2 = x

x = 1.13933 moles * 310 grams /mole

x = 353.2 grams. As you can see, even with my rounding I'm only out 0.3 of a gram. DON'T FORGET TO PUT THIS TO THE PROPER SIG DIGS IF SOMEONE ELSE IS GOING TO SEE IT.

Middle Panel

Short Answer C

Equation

2HCl + Mg ===> H2 + MgCl2

The object of the first part of the game is to find the number of moles of H2.

<em><u>Step One</u></em>

Find the moles of HCl

1 mole HCl = 35.5 + 1 = 36.5

n = given mass divided by molar mass

n = 49 grams / 36.5 = 1.34 moles.

The balanced equation tells you that for ever mole of H2 produced, you need 2 moles of HCl. That's what the balance numbers are for.

So the number of moles of H2 is 1.34 / 2 = 0.671 moles of H2.

Now we come to Part II. We have to use an new friend of yours that I have seen only once before from you.

Find V using PV = nRT

R is going to be in kPa so the value of R = 8.314

V = ???

n = 0.671 moles

T = 25 + 273 = 298oK

P = 101.3 kPa

101.3 * V= 0.671*8.314 * 298

V = 0.671 * 8.314 * 298 / 101.3

V = 16.4

The answer is C and again, I have rounded almost everything except R, although it can go out to 8 places.

Right Panel

I can't see the panel. I don't know what the problem is. Never mind I got it. I'm going to be a little skimpy on this one since I've done two like it and they are long.

LiOH + HBr ===> LiBr + H2O and the equation is balanced.

You have to figure out the moles of LiOH and HBr. Use the LOWEST number of moles

n_LiOH = given mass / molar mass = 117/(7 + 16 + 1) = 117 / 24 = 4.875 moles

n_HBr = given mass / molar mass =  141/(1 + 80) = 141 / 81 = 1.741 moles

HBr is the lower number. That's all the LiBr you are going to get is 1.741. There is no adjustment to be made from the balance equation.

n = given mass / molar mass  multiply both sides by the molar mass

n * Molar mass (LiBr) = n * (7 + 80) = 1.741 * 87 = 151 grams of

The answer is C


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2 years ago
What is the mass of helium atom whose atomic weight is 4.003 g/mol?
tino4ka555 [31]

Answer:

Atoms He (Avogadro’s number) → Moles of He (molar mass of He) → Mass of He

• molar mass of He (from the periodic table) = 4.003 g/mol

• Avogadro’s Number: Avogadro’s number gives us the number of entities present in 1 mole: 6.022 × 1023 He atoms in 1 mole of He

hope this is help full please mark me Brainliest

4 0
2 years ago
A voltaic cell has a zinc anode and a copper cathode. They are connected by a wire but no salt bridge. What can you predict will
Allisa [31]

The prediction is that B. The electrons will flow to the zinc anode where a negative charge will build up and eventually halt the reaction.

<h3>What is zinc?</h3>

This is known as a chemical element, of the periodic table, that is essential to life and is one of the most widely used metals. Zinc is of considerable commercial importance.

Without the salt bridge, positive and negative charges will build up around the electrodes causing the reaction to stop.

Hence, we know that the purpose of the salt bridge is to keep the solutions electrically neutral and allow the free flow of ions from one cell to another.

Read more about<em> zinc</em> here:

brainly.com/question/25764334

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4 0
2 years ago
Review this balanced neutralization reaction: HBr + KOH KBr + H2O. Which substance is the base?
Olegator [25]
B KOH
I would say this is the base for the compound substance
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Compare the spectra produced by incandescent and fluorescent sources. Why is there a difference?
Inessa [10]
Both have a continuous light spectra the fluorescent source makes a spectra with more intense bands of mercury
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