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madam [21]
4 years ago
10

5. How can you tell the difference between CuS and Cu2S

Chemistry
1 answer:
puteri [66]4 years ago
6 0

Answer:

Density, melting point. and magnetic properties  

Explanation:

I can think of three ways.

1. Density

The density of Cu₂S is 5.6 g/cm³; that of CuS is 4.76 g/cm³.

It should be possible to distinguish these even with high school equipment.

2. Melting point

Cu₂S melts at 1130 °C (yellowish-red); CuS decomposes at 500 °C (faint red).

A Bunsen burner can easily reach these temperatures.

3. Magnetic properties

You can use a Gouy balance to measure the magnetic susceptibilities.

In Cu₂S the Cu⁺ ion has a d¹⁰ electron configuration, so all the electrons are paired and the solid is diamagnetic.

In CuS the Cu²⁺ ion has a d⁹ electron configuration, so all there is an unpaired electron and the solid is paramagnetic.

A sample of Cu₂S will be repelled by the magnetic field and show a decrease in weight.

A sample of CuS will be attracted by the magnetic field and show an increase in weight.

In the picture below, you can see the sample partially suspended between the poles of an electromagnet.

 

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Suppose that in the citric acid cycle, oxalacetate is labeled with 14C in the carboxyl carbon farthest from the keto group. Wher
Nadusha1986 [10]

Answer:

All of alpha-ketoglutarate formed in the citric acid cycle would contain the radioactive ^{14}C while none of succinate would contain ^{14}C, and all of carbon dioxide released would contain ^{14}C.

Explanation:

When oxaloacetate in the citric acid cycle is labeled with ^{14}C in carboxyl carbon atom which is farthest from keto group, alpha ketoglutarate formed from this oxaloactetate has the full radioactive label. In the next step, the carboxylic group (that contains the ^{14}C) is eliminated in the form of the release of the carbon dioxide and succinate is formed. Succinate thus will not have radioactivity. CO_2 released had all the radioactivity.

8 0
3 years ago
Given the following Fischer projection: Fischer projection for an entantiomer of 2-bromo-2,3-dihydroxypropanal with the bromine
harina [27]

Answer:

Explanation:

Stereoisomers are two or more atoms that  have the same bonding order of atoms but there is a difference  spatial arrangement of  the  atoms in space.

A plane of symmetry divides a molecule into two equal halves.

A chiral stereoisomer are not superimposed on a mirror image , Hence they do not posses a plane of symmetry.

As a result to that. these non-superimposable mirror images are said to be Enantiomers.

However, a Fischer Projection emanates from a two - dimensional figure which is used for presenting a three - dimensional organic molecules.

From the given question;

Fischer projection for an enantiomer of 2-bromo-2,3-dihydroxypropanal with the bromine oriented horizontally to the left and the hydroxide group oriented horizontally to the right.

we can sketch the way the enantiomer of 2-bromo-2,3-dihydroxypropanal can  be seen like the one shown below:

              CH₂OH

                   |

                   |

                   |

Br -------------|----------------OH

                   |

                   |

                   |

                 CHO

The objective of this question is to drawn the perspective formula of the molecule.

So , from the attached file below; we can see the perspective formula of the molecule in a well structured 3-D format.

5 0
3 years ago
What is the percent by mass of water in the hydrate? %
dusya [7]

Sorry I can't tell you the answer but, I can tell you something...

Dividing the mass of the water lost by the mass of hydrate used is equal to the fraction of water in the compound. Multiplying this fraction by 100 gives the percent water in the hydrate.

How to find it?

Divide the mass of the water lost by the mass of hydrate and multiply by 100. The theoretical actual percent hydration percent water can be calculated from the formula of the hydrate by dividing the mass of water in one mole of the hydrate by the molar mass of the hydrate and multiplying by 100.

8 0
3 years ago
This is a mixture that has different properties throughout.
Olin [163]

Answer:

Heterogenous mixture is a mixture that has different properties throughout.

Explanation:

Mixture refers to substances that are not chemically mixed together, that is, they can easily be separated by physical methods. There are two major types of mixture; these are heterogeneous and homogeneous mixtures. Homogeneous mixtures refer to those mixtures that are uniform in composition. A good example of this is tap water. Heterogeneous mixture on the other hand refers to those mixtures, which are not uniform in composition. A good example of this is a mixture of water and sand.  

4 0
3 years ago
How many molecules of hydrogen gas are present in a 750 ml<br> container at STP?
BabaBlast [244]

Answer: 1.99 x 10²² molecules H2

Explanation:First we will solve for the moles of H2 using Ideal gas law PV= nRT then derive for moles ( n ).

At STP, pressure is equal to 1 atm and Temperature is 273 K.

Convert volume in mL to L:

750 mL x 1 L / 1000 mL

= 0.75 mL

n = PV/ RT

= 1 atm ( 0.75 L ) / 0.0821 L.atm/ mole.K ( 273 K)

= 3.3x10-² moles H2

Convert moles of H2 to atoms using Avogadro's Number.

3.3x10-² moles H2/ 6.022x10²³ atoms H2 / 1 mole H2

= 1.99x10²² atoms H2

4 0
3 years ago
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