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mel-nik [20]
3 years ago
12

A 67.2 g sample of a gold and palladium alloy contains 2.49 * 1023 atoms. what is the composition (by mass) of the alloy?

Chemistry
1 answer:
jasenka [17]3 years ago
5 0
One mole of any substance contains 6.022 x 10^23 atoms
Therefore, number of moles containing <span>2.49×10^23 atoms can be calculated as follows:
number of moles = (2.49 x 10^23) / (6.022 x 10^23) = 0.4135 moles

From the periodic table:
molecular mass of gold = 197 grams
molecular mass of palladium = 106.4 grams
Therefore:
molar mass of gold = 197 grams
molar mass of palladium = 106.7 grams

First equation:
moles of gold + moles of palladium = </span>0.4135<span> moles

Second equation:
mass of gold + mass of palladium = 67.2 grams
mass can be written as: mass = number of moles x molar mass
therefore:
(mass of gold + mass of palladium) can be rewritten as:
moles of gold x 197 + moles of palladium x 106.4 = 67.2 grams

Now, we have two equations (highlighted in bold) in two unknowns, we can solve them simultaneously to get the number of moles of each element as follows:
From equation one:
moles of gold = </span>0.4135<span> - moles of palladium
Substitute with this in equation 2:
</span>(0.4135 - moles of palladium) x 197 + moles of palladium x 106.4 = 67.2
 81.4595 - 197 moles of palladium + 106.4 moles of palladium = 67.2
81.4595 - 67.2 = 197 moles of palladium - 106.4 moles of palladium
14.2595 = 90.6 moles of palladium
moles of palladium = 0.1574 moles
Substitute in equation 1 to get moles of gold:
moles of gold = 0.4135 - 0.1574 = 0.2561 moles

Now, the last step is to convert the number of moles to mass:
mass = number of moles x molar mass
mass of gold = 0.2561 x 197 = 50.4517 grams
mass of palladium = 0.1574 x 106.4 = 16.74736 grams
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siniylev [52]
That is not a question/problem and makes no sense whatsoever
4 0
3 years ago
TRY H Vele
Strike441 [17]
<h3>Answer:</h3>

Al- [Ne] 3s²3p¹

As- [Ar] 4s²3d¹⁰ 4p³

Explanation:

  • Electron configuration of an element shows the arrangement of electrons in the energy levels or orbitals in the atom.
  • Noble-gas configuration involves use of noble gases to write the configuration of other elements.
  • This is done by identifying the atomic number of the element and then identifying the noble gas that comes before that particular element on the periodic table.
  • For example:
  1. Aluminium: The atomic number of Al is 13. The noble gas before Aluminium is Neon which has 10 electrons. Therefore the remaining 3 electrons fills up the 3s and 3p sub orbitals.
  • Thus, the noble-gas configuration of Al is [Ne] 3s²3p¹

     2.  Arsenic, Atomic number is 33

  • Noble gas before Arsenic is Ar,. Argon has 17 electrons, then the remaining electrons fills up the 4s, 3d and 4p sub-orbitals.
  • Thus, the noble-gas configuration of As is [Ar] 4s²3d¹⁰ 4p³
6 0
3 years ago
Dana is trying to determine if an unknown sample is a pure substance or not. The sample has a cloudy white color, and it seems e
Firdavs [7]

Answer:

Dana filtered the sample and larger granules of the sample were left behind.

Explanation:

If a substance is pure, it will have a uniform composition throughout. It will not separate into particles of various sizes.

One of the characteristics of pure substances is that they are homogeneous. A mixture is definitely made up of particles of various sizes.

Since the particles was filtered and larger granules were left behind, the sample has been separated by a physical method (filtration). Only a mixture can be separated by physical methods. It is not a pure substance.

5 0
3 years ago
The period of daylight experienced each day on every part of Earth would be shorter if which one of the following changes occurr
lilavasa [31]

Answer:

c

Explanation:

5 0
3 years ago
The electron dot structure for CI is
finlep [7]
The correct option is C.
A Lewis dot diagram is a representation of the valence electron of  an atom, which uses dot around the symbol of the atom. Chlorine has seven electrons in its outermost shell, these seven electrons are arranged in form of dot around the atom of chlorine. If you count the number of dot given in option C, you will notice that they are seven.
6 0
3 years ago
Read 2 more answers
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