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astraxan [27]
3 years ago
6

A student was performing a separation of a mixture of organic compounds. The final step of the process involved a filtration of

the analyte from an aqueous solution. After drying the filtered solid for a very short period time, they took the melting point of the compound. The measured melting point range of the compound was 106 – 113.8 0C, while the literature melting point of the compound was 122.3 0C. The above scenario is a very common one in organic labs.
1. Do you think their sample was pure?
2. If not, then what do you think could be the source of error.
3. How do you think this error can be minimized?
Chemistry
1 answer:
Ahat [919]3 years ago
8 0

Answer:

1) No

2) The solvent contaminated the analyte

3) The solvent should be evaporated properly before washing and drying the analyte

Explanation:

During separation of organic compounds, solvents are used. These solvents are able to contaminate the analyte and lead to a large difference in melting point of solids obtained.

However, the error can be minimized by evaporating the solvent before washing, drying and melting point determination of the solid.

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Lubov Fominskaja [6]

Answer:

1000ml/1L

Explanation:

8 0
2 years ago
There are three sets of sketches below, showing the same pure molecular compound (hydrogen chloride, molecular formula ) at thre
RideAnS [48]

Answer:

The correct answer is - option C.

Explanation:

Given: the melting point of HCl is

-114.8 °C, which suggests that below this temperature HCl will be solid.

and, since the boiling point of HCl is - 85.1 °C. It is also suggested that above this temperature HCl will be gas, Therefore.

Solid -114.8  - Ordered arrangement

Liquid -85.1c  - Less orderly arranged

Gaseous - Least orderly arranged

Thus, at —90 °C, HCl will be present 'in the liquid state,  At — 1 °C, HCl will be present in the gaseous state and at -129 °C, HCl will be present in the solid-state. So, the molecules will be organized in a more orderly manner .

Thus, the correct answer is - option C

8 0
3 years ago
How many liters of CO2 are formed when 14.0 g of CaCO3 react at 1.00 atm and 1000K
Gnesinka [82]

Answer: 11.5

Explanation:

7 0
3 years ago
Read 2 more answers
When a mercury-202 nucleus is bombarded with a neutron, a proton is ejected. What element is formed?
Galina-37 [17]

That will make a gold-202 nucleus.

<h3>Explanation</h3>

Refer to a periodic table. The atomic number of mercury Hg is 80.

Step One: Bombard the \displaystyle ^{202}_{\phantom{2}80}\text{Hg} with a neutron ^{1}_{0}n. The neutron will add 1 to the mass number 202 of ^{202}_{\phantom{2}80}\text{Hg}. However, the atomic number will stay the same.

  • New mass number: 202 + 1 = 203.
  • Atomic number is still 80.

^{202}_{\phantom{2}80}\text{Hg} + ^{1}_{0}n \to ^{203}_{\phantom{2}80}\text{Hg}.

Double check the equation:

  • Sum of mass number on the left-hand side = 202 + 1 = 203 = Sum of mass number on the right-hand side.
  • Sum of atomic number on the left-hand side = 80 = Sum of atomic number on the right-hand side.

Step Two: The ^{203}_{\phantom{2}80}\text{Hg} nucleus loses a proton ^{1}_{1}p. Both the mass number 203 and the atomic number will decrease by 1.

  • New mass number: 203 - 1 = 202.
  • New atomic number: 80 - 1 = 79.

Refer to a periodic table. What's the element with atomic number 79? Gold Au.

^{203}_{\phantom{2}80}\text{Hg} \to ^{202}_{\phantom{2}79}\text{Au} + ^{1}_{1}p.

Double check the equation:

  • Sum of mass number on the left-hand side = 203 = 202 + 1 = Sum of mass number on the right-hand side.
  • Sum of atomic number on the left-hand side = 80 = 79 + 1 = Sum of atomic number on the right-hand side.

A gold-202 nucleus is formed.

6 0
2 years ago
When 10.0 grams of sulfur reacts with fluorine gas at a pressure of 2.69 atmosphere in a 5.00 L container at 0.00 degrees Celsiu
Gwar [14]

Answer:

74.1%

Explanation:

Based on the reaction:

S₈ + 16F₂ → 8SF₄

<em>1 mole of sulfur reacts with 16 moles of F₂ to produce 8 moles of SF₄</em>

<em />

To solve this question we must find the moles of each reactant in order to find the moles of SF₄. Thus, we can find the theoretical mass produced. Percent yield is:

Percent yield = Actual yield (25.0g) / Theoretical yield * 100

<em>Moles S₈: 256.52g/mol</em>

10.0g * (1mol / 256.52g) = 0.0390 moles

<em>Moles F₂:</em>

<em>PV = nRT</em>

PV/RT = n

<em>Where P is pressure in atm, V is volume in liters, R is gas constant and T is absolute temperature (0°C = 273.15K)</em>

2.69atm*5.00L / 0.082atmL/molK*273.15K = n

0.600 moles = n

For a complete reaction of 0.600 moles F₂ are required:

0.600mol F₂ * (1mol S₈ / 8 mol F₂) = 0.075 moles S₈

As there are just 0.0390 moles, S₈ is limiting reactant.

The theoretical moles and mass of SF₄ -Molar mass: 108.07g/mol- is:

0.0390 moles S₈ * (8mol SF₄ / 1mol S₈) = 0.312 moles SF₄ * (108.07g) =

33.7g

Percent yield = 25.0g / 33.7g * 100

= 74.1%

6 0
2 years ago
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