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julia-pushkina [17]
1 year ago
8

Calculate the atomic mass of X. The three X isotopes have atomic mass and relative abundances of 27.9769 amu (92.2297%), 28.9765

amu (4.6832%) and 29.9738 amu (3.0872%). What is this atom?
Co


Al


Ni


Si
Chemistry
1 answer:
Irina18 [472]1 year ago
7 0
<h3>Answer:  Si   (choice D)</h3>

This is the element Silicon.

=========================================================

Explanation:

First convert each percentage to its decimal form.

For example, 92.2297% converts to 0.922297 after moving the decimal point two spots to the left.

After doing that, multiply those decimal values with their respective atomic mass unit (amu) values.

  • 27.9769 * 0.922297 = 25.8030109393
  • 28.9765 * 0.046832 = 1.357027448
  • 29.9738 * 0.030872 = 0.9253511536

Then we add up the results

25.8030109393 + 1.357027448 + 0.9253511536 = 28.0853895409

That rounds to about 28.085

Then look at the periodic table to see the atomic mass of Cobalt (Co), Aluminum (Al), Nickel (Ni) and Silicon (Si). The mass values listed in the periodic table are weighted averages of all the isotopes. The units for the mass are still in amu.

  • Cobalt = 58.933
  • Aluminum = 26.982
  • Nickel = 58.693
  • Silicon = 28.085

We have a match with silicon, showing that <u>choice D</u> is the final answer.

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Because these characteristics do not depend on the amount of sample, nor do they change according to conditions.
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CO(g) + 3 H2(g) → CH4(k) + H2O(g) + heat
weqwewe [10]

Explanation:

AH is negative because the reaction gives out heat (exothermic).

AS is negative because the total entropy of the reactants is greater than that of the products (there are 4 moles of gas on reactant side compared to only 1 mole on the product side). Thus, the reactants are said to be "messier" than the products.

AG is negative at lower temperatures because at low temperatures, -TAS is more negative, resulting in the negative sign of AG.

Hope this helps.

8 0
3 years ago
What is the number if moles of nitrogen gas which react with 18 g of magnesium to form magnesium nitride compound?(mg=24,N=14)
makvit [3.9K]

Answer:

It is true. a) 0.25 mol

Explanation:

<em>Hello </em><em>there?</em>

To begin solving this problem, you have to write down the chemical equation and make sure it is well balanced.

The chemical equation is;

3Mg(s) + N2(g) => Mg3N2(s)

1 mole of Mg = 24g

We have 18g of Magnesium (Mg) reacting with Nitrogen gas (N2)

From our equation,

Mole ratio = 3 : 1, (Mg : N2)

1 mol Mg = 24g

x mol Mg = 18g

x mol Mg = (18/24) = 0.75 mol Mg

But mole ratio = 3 : 1 (Mg : N2)

This means that 3 => 0.75 mol Mg

What about ratio 1 of N2?

N2 = (0.75 mol ÷ 3)/1

= 0.25 mol N2

<em>I </em><em>hope</em><em> </em><em>this </em><em>helps</em><em> </em><em>you </em><em>to </em><em>understand</em><em> </em><em>better</em><em>.</em><em> </em><em>Ha</em><em>v</em><em>e </em><em>a </em><em>nice </em><em>studies.</em><em> </em><em />

6 0
2 years ago
the density of pure gold (au) is 19.3 g/cm3. what is the mass of a block of gold that measures 1.2 cm x 5.00 cm x 3.20 cm? pleas
Julli [10]

The density of pure gold (au) is 19.3 g/cm3. what is the mass of a block of gold that measures 1.2 cm x 5.00 cm x 3.20 cm? please show work.


Given: Density of pure gold = 19.3 g /cm^3

Measurement of block of gold =1.2 cm x 5.00 cm x 3.20 cm

To calculate : mass of gold

Formula used: Density = Mass / Volume

Volume = 1.2 cm x 5.00 cm x 3.20 cm = 19.2 cm^3

Mass of gold = Density X volume = 19.3 g /cm^3 X 19.2 cm^3  = 370.56 g

4 0
3 years ago
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cricket20 [7]

Answer: Mothballs have weak intermolecular forces.

No all substances do not behave like mothballs at normal conditions. Example: benzene , chloroform

Explanation:

Sublimation is a process of converting a substance from solid state to gaseous state without the formation of liquid at constant temperature.

A substance which undergoes sublimation is called as sublimating substance.

As mothballs is made of napthalene which has weak inter molecular forces of attraction between its molecules, it directly sublimes into gaseous state without leaving any residue and is called as a sublimating substance.

Not all substances behave like mothballs at normal conditions. Example: benzene , chloroform

8 0
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