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sasho [114]
3 years ago
11

Each of the two different solids A and B melts at 133 o C. A sample of an unknown solid melts around 133 o C, and is either A or

B. How will you determine the identity of the unknown solid
Chemistry
1 answer:
rusak2 [61]3 years ago
4 0

Answer:

See explanation

Explanation:

The melting point range of a pure compound is about 1-2ºC of the expected melting point. An impure solid melts within a range   that is both larger than that of the pure substance  (>1ºC) and begin at a  lower temperature because impurities decrease the meting point. A melting range of 5º or more  indicates that a compound is impure.

Since the melting points of A and B are estimated  at 133 o C, the melting point range for each pure substance must be slightly different from each other. The melting point of the unknown is measured and its range is compared with the melting point ranges of pure A and B then decision can  now be made about the identity of the unknown solid.

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Measurements show that unknown compound X has the following composition: element mass % carbon 41.0% hydrogen 4.58% oxygen 54.6%
anastassius [24]

Answer:

CHO

Explanation:

Carbon = 41%,  Hydrogen = 4.58%, oxygen = 54.6%

Step 1:

Divide through by their respective relative atomic masses

41/ 12,         4.58/1,         54.6/16

3.41              4.58            3.41

Step 2:

Divide by the lowest ratio:

3.41/3.41,      4.58/3.41,     3.41/3.41

1,                    1,                  1

Hence the empirical formula is CHO

8 0
3 years ago
Scientists have categorized trees based on whether they keep or lose their leaves each year. Another logical way to categorize t
Zolol [24]

Answer:

D

Explanation:

I think but it is an better attempt than the other guy answer.

5 0
3 years ago
Give the formula of each coordination compound. Include square brackets around the coordination complex. Do not include the oxid
rodikova [14]

Answer:

sodium hexachloroplatinate(IV)- Na2[PtCl6]

dibromobis(ethylenediamine)cobalt(III) bromide- [Co(en)2Br2]Br

pentaamminechlorochromium(III) chloride-[Cr(NH3)5Cl]Cl2

Explanation:

The formulas of the various coordination compounds can be written from their names taking cognisance of the metal oxidation state as shown above. The oxidation state of the metal will determine the number of counter ions present in the coordination compound.

The number ligands are shown by subscripts attached to the ligand symbols. Remember that bidentate ligands such as ethylenediamine bonds to the central metal ion via two donors.

4 0
3 years ago
Under identical conditions, separate samples of O2 and an unknown gas were allowed to effuse through identical membranes simulta
scoray [572]

Answer:

70.77 g/mol is the molar mass of the unknown gas.

Explanation:

Effusion is defined as rate of change of volume with respect to time.

Rate of Effusion=\frac{Volume}{Time}

Effusion rate of oxygen gas after time t = E=\frac{4.64 mL}{t}

Molar mass of oxygen gas = M = 32 g/mol

Effusion rate of unknown gas after time t = E'=\frac{3.12 mL}{t}

Molar mass of unknown gas = M'

The rate of diffusion of gas, we use Graham's Law.

This law states that the rate of effusion or diffusion of gas is inversely proportional to the square root of the molar mass of the gas. The equation given by this law follows:

\text{Rate of effusion}\propto \frac{1}{\sqrt{\text{Molar mass of the gas}}}

\frac{E}{E'}=\sqrt{\frac{M'}{M}}

\frac{\frac{4.64 mL}{t}}{\frac{3.12 mL}{t}}=\sqrt{\frac{M'}{32 g/mol}}

M' = 70.77 g/mol

70.77 g/mol is the molar mass of the unknown gas.

8 0
3 years ago
Information-
tekilochka [14]

Answer:

So first thing to do in these types of problems is write out your chemical reaction and balance it:

Mg + O2 --> MgO

Then you need to start thinking about moles of Magnesium for moles of Magnesium Oxide. Based on the above equation 1 mole of Magnesium is needed to make one mole of Magnesium Oxide.

To get moles of magnesium you need to take the grams you started with (.418) and convert to moles by dividing by molecular weight of Mg (24.305), this gives you .0172 moles of Mg.

The theoretical yield would be the assumption that 100% of the magnesium will be converted into Magnesium Oxide, so you would get, based on the first equation, .0172 mol of MgO. Multiplying this by the molecular weight of MgO (24.305+16) gives us .693 g of MgO.

The percent yield is what you actually got in the experiment, and for this you subtract off the total mass from the crucible mass, or 27.374 - 26.687, which gives .66 g of MgO obtained.

Percent yield is acutal/theoretical, .66/.693, or 95.24%.

I'll let you do the same for the second trial, and average percent yield is just an average of the two trials percent yield.

Hope this helps.

6 0
3 years ago
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