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?

Answers

Answer 1

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.


Related Questions

PLEASE PLEAS HELP Which of the following compounds is insoluble in water?
a) ZnSO4
b) K2SO4
c) Na2CO3
d) Ag2CO3

Answers

Answer:

Your answer is d

Explanation: silver carbonate Ag2CO3 is insoluble in water

Which of the following evidence supports the theory of plate tectonics

Answers

The theory of plate tectonics states that the Earth's solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper portion of the mantle.,Thus, at divergent boundaries, oceanic crust is created that’s what plate tectonics means hoped that helped

Answer:

seafloor spreading

Explanation:

i took the test

A sample of an ideal gas has a volume of 2.23 L at 289 K and 1.05 atm. Calculate the pressure when the volume is 1.08 L and the temperature is 304 K. P= atm

Answers

Answer:

2.28 atm

Explanation:

V₁ = 2.33L,  V₂ = 1.08L

T₁ = 289K,  T₂ = 304K

P₁ = 1.05 atm, P₂ = ?

Where V₁ and V₂ are initial and final volume respectively

T₁ and T₂ are initial and final temperature respectively

P₁ and P₂ are initial and final pressure respectively

The formula to be used here is the general gas equation:

P₁V₁/T₁=P₂V₂/T₂

1.05 × 2.23/289 = P₂ × 1.08/304

P₂ × 1.08 × 289 = 1.05 × 2.23 × 304

P₂ = (1.05 × 2.23 ×304) ÷ (1.08 × 289)

P₂ = 711.82 ÷ 312.12

P₂ = 2.28 atm

The smallest form of matter that still retains the properties of an element

Answers

Answer:

atom

Explanation:

the atom is the smallest form.

Although there are smaller forms of matter (subatomic quarks, photons, electrons) an atom is the smallest that a form of matter could be that still possesses the properties of that element. An atom is classified into being a certain element based on how many protons it has.

SOMEONE PLEASE HELPPP​

Answers

A is the correct awnser Beacuse it ether right kne

Which element contains one set of paired and three unpaired electrons in its fourth and outer main energy level? ​

Answers

Explanation:

Phosphorus (P) because of the 5 valence electrons total, 3 of them are in the 3p sublevel, and according to Hund's rule, they "single-fill" each orbital first.

The atoms of which element will gain electrons to form an ion?
oxygen
calcium
lithium
mercury

Answers

Explanation:

Oxygen will gain electrons to form ion (O²⁻).

Calcium loses electron to form ion (Ca²⁺)

Lithium loses electron to form ion (Li⁺)

Mercury loses electron to form ion (Hg²⁺)

Here it is stated in question that the element will gain electron it means electron bears negative charge.

Therefore,

Option A is correct ✔.

Match the following terms and definitions.
1. major ecological grouping of plants and animals
food chain
biome
environmental factor
decomposers
2. bacteria and fungi that break down dead matter
a state of change in which the end result is equal or
3.
balanced
the basic relationships that show how a community of plants,
animals, and bacteria live and grow and how these living
4. things are dependent on each other as well as the Sun, soil,
and other nonliving parts of their environment; a cycle of
relationships
line of plants and animals that shows the order in which
5.
organisms are eaten
a condition or conditions of the nonliving surroundings, such
6.
as light, temperature, water, and so on
ecosystem
dynamic equilibrium

Answers

Answer:

major ecological grouping of plants and animals

food chain

*biome*

bacteria and fungi that break down dead matter

*decomposers*

a state of change in which the end result is equal or

balanced

*dynamic equilibrium*

the basic relationships that show how a community of plants,

animals, and bacteria live and grow and how these living

*ecosystem*

things are dependent on each other as well as the Sun, soil,

and other nonliving parts of their environment; a cycle of

relationships

line of plants and animals that shows the order in which

*Food chain*

organisms are eaten

a condition or conditions of the nonliving surroundings, such

*environmental factor*

Explanation:

Which statement best demonstrates how data from a global positioning system (GPS) can be used to lessen the effects of a
wildfire? (1 point)
GPS data can be used by people to quickly evacuate an area because of a wildfire
GPS data can be used by scientists to predict weather patterns that can lead to a wildfire
GPS data can be used by firefighters to identify the boundaries of a wildfire
GPS data can be used by first responders to calculate the safest route to a wildfire

Answers

Answer: here is your answer

Explanation: You are visiting your Grandmother and notice that she is eating a balanced diet, taking vitamins, getting the proper amount of sleep and is not overweight. Despite her healthy lifestyle, she appears run down and tired. You realize that it's due to her lack of physical activity. Write a convincing letter to your grandma explaining the benefits of participating in regular physical activity.

which of the two pure substance consists of different types of Element​

Answers

Answer:Two Main Types of Pure Substances

Elements and compounds are the two types of pure substances. Examples of common elements include carbon, nitrogen and hydrogen. They consist of one type of atom and cannot break down into something else. Every pure carbon substance, for example, has the same particles in it.

Explanation:I think

Which statement describes how this rock was likely formed?
slow cooling of magma beneath the surface of Earth
rapid cooling of magma beneath the surface of Earth
slow cooling of lava on the surface of Earth
rapid cooling of lava on the surface of Earth

I will mark Brainlyest

Answers

Answer:

A

Explanation:

Slow cooling of magma beneath the surface of earth

To solve this we must be knowing each and every concept related to rock and its formation. Therefore, the correct option is option A among all the given options.

What is rock?

Rock is a naturally occurring mineral aggregate that is cohesive and composed of one or even more minerals. These aggregates often take the shape of recognisable and mappable volumes and are the fundamental building block of the solid Earth.

Mineral crystals as well as the sorts of rocks that serve as their hosts cycle through many forms as geologic materials. Temperature, weight, time, and variations in the climate in the Earth's crust and on its surface all play a role in the process. Slow cooling of magma beneath the surface of Earth is the  statement that best describes the formation of rock.

Therefore, the correct option is option A.

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A chemical engineer must calculate the maximum safe operating temperature of a high-pressure gas reaction vessel. The vessel is a stainless-steel cylinder that measures 41.0cm wide and 49.2cm high. The maximum safe pressure inside the vessel has been measured to be 3.70MPa. For a certain reaction the vessel may contain up to 2.50kg of dinitrogen difluoride gas.

Required:
Calculate the maximum safe operating temperature the engineer should recommend for this reaction. Write your answer in degrees Celsius. Be sure your answer has the correct number of significant digits.

Answers

Answer:

[tex]T=2.78x10^3 \°C[/tex]

Explanation:

Hello,

In this case, considering that the safe temperature may be computed via the ideal gas law as we now the pressure, mass and volume via the dimensions:

[tex]V=\pi r^2 h=\pi *(41.0cm)^2*49.2cm=2.60x10^5cm^3*\frac{1L}{1000cm^3} =260L[/tex]

The pressure in atm is:

[tex]P=3.70MPa*\frac{1x10^6Pa}{1MPa} \frac{1atm}{101325Pa} =36.5atm[/tex]

And the moles considering the mass and molar mass (66 g/mol) of dinitrogen difluoride (N₂F₂):

[tex]n_{N_2F_2}=2.50kg*\frac{1000g}{1kg}*\frac{1mol}{66g} =37.9mol[/tex]

In sich a way, by applying the ideal gas equation, which is not the best assumption but could work as an approximation due to the high temperature, the temperature, with three significant figures, will be:

[tex]T=\frac{PV}{nR}=\frac{36.5Pa*260L}{37.9mol*0.082\frac{atm*L}{mol*K} }\\ \\T=3053.6K-273.15\\\\T=2.78x10^3 \°C[/tex]

Best regards.

A liquid has a volume of 62.7 mL and a density of 2.59 g/mL. What is its mass? (show all work)

Answers

Answer:

162.4

Explanation:

The formula for mass is density* volume so 62.7 multiplied by 2.59 equals 162.393. then you round so your anwser would be 162.4

noble gas notation for titanium

Answers

Answer:

Titanium [Ar] 3d2 4s2

Explanation:

Which of the following represents a species with 16 protons and 18 electrons? A) Ar B) S C) S²⁻ D) Si⁴⁻ E) S²⁺ Question 5 of 40

Answers

Answer:S²⁻

Explanation:

Sulphur is in group 16. The atomic number of sulphur is 16.

However, sulphur can accept two electrons to form the sulphide ion S²⁻ which contains 18 electrons, hence the answer provided above.

Based on the visible cell structure, which of the following statements is true?

Answers

Answer:I think it would be the third one.

Explanation:

is a renewable resource used for the generation of electricity.
A. Natural gas
B. Coal
C. Petroleum
O D. Biomass

Answers

Answer:

its natural gas because i had something like this

Explanation:

The renewable energy sources, such as biomass, geothermal resources, water, wind, etc. are called the natural resources. These can be converted into clean and usable energy. The correct option is D.

What is Renewable energy?

The energy which is derived from the natural sources which are replenished at a higher rate than they are consumed is defined as the Renewable energy. The renewable energy generating produce lower emissions than burning the fossil fuels.

The word biomass refers to the organic plant matter which is converted into fuel and used as an energy source. The biomass fuel is considered as an important renewable and sustainable source of energy. It is used for the production of electricity.

The organic materials like wood, agricultural wastes, etc. acts as the excellent sources to produce biomass fuel. It is possible to burn the biomass fuel directly and later converted into methane and ethanol biofuels.

Thus the correct option is D.

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The solubility of silver(I)phosphate at a given temperature is 2.43 g/L. Calculate the Ksp at this temperature. After you calculate the Kspvalue, take the negative log and enter the (pKsp) value with 2 decimal places.

Answers

Answer:

Kps = 3.07 x 10⁻⁸

pKsp= 7.51

Explanation:

First, we calculate the molar solubility of  silver(I)phosphate (Ag₃PO₄) from the solubility in g/L by using its molar mass (418.6 g/mol):

2.43 g/L x 1 mol/418.6 g = 5.8 x 10⁻³ mol/L= s

Now, we have to write the ICE chart for the aqueous equilibrium of Ag₃PO₄ as follows:

     Ag₃PO₄(g) ⇄ 3 Ag⁺(aq) + PO₄³⁻

I                               0              0

C                            +3s           +s

E                            3s               s

Ksp = [Ag⁺]³[PO₄³⁻]= (3s)³s= 27s⁴

Since s=5.8 x 10⁻³ mol/L, we calculate Ksp:

Ksp= 27(5.8 x 10⁻³ mol/L)⁴= 3.07 x 10⁻⁸

The pKsp value is:

pKsp= - log Ksp = -log (3.07 x 10⁻⁸) = 7.51

True or False: Particles that are moving faster have a higher temperature

Answers

Answer:

true

Explanation:

I'm not sure why cause I dont know how to explain but it's TRUE

Answer:

True  

Explanation:

The particles moving faster in a substance the hotter it gets.

a change of matter is a physical change
True or False​

Answers

Answer:

true

Explanation:

hope it helps

Answer:

I'm pretty sure it's true

Explanation:

20 characters

Which of the following is NOT a strong electrolyte?
:

Answers:
Na2SO4
KI
CaCl2
LiOH
C6H1206

Answers

Answer:

C6H1206

Explanation:

C6H12O6 is a monomer of carbohydrates also known as glucose, so it is not an electrolyte at all.

How many atoms of Chlorine are in 1.00 mol of Chlorine gas?
6.022 x 10∧23
3.01 x 10∧23
6.022 x 10∧24

Answers

Answer:

6.02 × 10²³ atoms Cl₂

Explanation:

Avagadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Step 1: Define

1.00 mol Cl₂ (g)

Step 2: Use Dimensional Analysis

[tex]1.00 \hspace{3} mol \hspace{3} Cl_2(\frac{6.02(10)^23 \hspace{3} atoms \hspace{3} Cl_2}{1 \hspace{3} mol \hspace{3} Cl_2} )[/tex] = 6.02 × 10²³ atoms Cl₂

What is the heat gjoules transferred by a chemical reaction to the reservoir of a calorimeter containing 135g of dilute aqueous solution (c=4.184 J/g^ C) the reaction causes the temperature of the reservoir to rise from 23.0 27.0 degrees * C

Answers

Answer:

Required heat = 2,259.36 N (approx)

Explanation:

Given:

Mass = 135 g

Specific heat (c) =4.184 J/gC

Change in temperature ΔT = 27-23 = 4 c

Find:

Required heat

Computation:

Q = mcΔT

Q = (135)(4.184)(4)

Required heat = 2,259.36 N (approx)

The heat transferred by the chemical reaction to the reservoir of a calorimeter containing 135 g of dilute aqueous solution is 2259.36 J

To solve this question, we'll begin by calculating the change in the temperature of the reservoir. This can be obtained as follow:

Initial temperature (T₁) = 23 °C

Final temperature (T₂) = 27 °C

Change in temperature (ΔT) =?

ΔT = T₂ – T₁

ΔT = 27 – 23

ΔT = 4 °C

Finally, we shall determine the heat transferred to the reservoir.

Change in temperature (ΔT) = 4 °C

Mass (M) = 135 g

Specific heat capacity (C) = 4.184 J/gºC

Heat (Q) =?

Q = MCΔT

Q = 135 × 4.184 × 4

Q = 2259.36 J

Therefore, the heat transferred by the chemical reaction to the reservoir of a calorimeter containing 135 g of dilute aqueous solution is 2259.36 J

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why are copper pipes used in place of old lead pipes for plumbing systems?

Answers

copper is lightweight, which makes it easier to work with (saving on labor costs) and also easier to extend over long stretches without supports. It's also less expensive than steel and lead-free.

how many grams of oxygen are there in 66.2 g of nitrous acid

Answers

Answer:

15.9994 grams

You can view more details on each measurement unit: molecular weight of Oxygen or grams The molecular formula for Oxygen is O. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles Oxygen, or 15.9994 grams.

Explanation:

Answer:

First you need to know the Chemical formula for Nitrous acid which is HNO₂

Explanation:

What was one main point of Dalton’s atomic theory?
A. That atoms were made up of positive and negative charges
B. That atoms changed as they formed compounds
C. That atoms has a nucleus at the center
D. That atoms made up the smallest form of matter

Answers

The main point of Dalton’s atomic theory is that the atoms are made up the smallest form of matter. Hence Option (D) is Correct

What is Dalton's Atomic Theory ?

The 5 main points of Dalton's Atomic theory was ;

Elements are composed of extremely small particles called atoms that are indivisible and indestructible

All atoms of a given element are identical; they have the same size, mass, and chemical properties

Atoms of 1 element are different from the atoms of all other elements

Compounds are composed of atoms of more than 1 element. The relative number of atoms of each element in a given compound is always the same.

Chemical reactions only involve the rearrangement of atoms. Atoms are not created or destroyed during chemical reactions.

Therefore, The main point of Dalton’s atomic theory is that the atoms are made up the smallest form of matter. Hence Option (D) is Correct

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Answer:

D is correct

Explanation:

1. Determine the electron-domain geometry and molecular geometry for each of the following.

a. SBr2
b. PI4+
c. IBr2−

2. The following three compounds all have the same general formula, XF4. Compare the electron-domain geometries of these three compounds and explain what characteristic(s) of the central atom causes differences in geometry.

a. SiF4:
b. SeF4:
c. XeF4:

Answers

Answer:

SBr2: Electron geometry-tetrahedral; molecular geometry-trigonal pyramidal

PI4+: Electron geometry-tetrahedral; molecular geometry-tetrahedral

IBr2−: Electron geometry- Trigonal bipyramidal ; molecular geometry- linear

Explanation:

In SBr2, the molecule is of the structure type AX2E2 hence it is based on a tetrahedron but have two lone pairs of electrons hence the molecular geometry is trigonal pyramidal.

PI4+ has four electron domains and all of them are bond pairs hence both electron geometry and molecular geometry are both tetrahedral.

IBr2- is of the structure type AX2E3 hence it is based on a trigonal bipyramd and has a linear molecular geometry.

2)

SiF4 has a tetrahedral molecular and electron domain geometry because the central atom(Si) has no lone pairs.

SeF4 has a trigonal bipyramidal electron geometry with the structure AX4E. Its molecular geometry is See-saw since it has one lone pair of electrons that causes a deviation from its ideal trigonal bypyramidal geometry.

XeF4 has  an octahedral electron domain geometry and the molecule is AX4E2. The two lone pairs are positioned above and below the plane of a square hence the molecule is square planar.

Which of the following contribute(s) to most of the mass of an atom? Question 5 options: A) Neutrons only B) Protons and electrons C) Protons and neutrons D) Protons only

Answers

Answer:

C

Explanation:

Hope this helps :)

The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the
А.
electron
B
proton
neutron
D
atom

Answers

Answer:

The answer is D - Atom

The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the atom.

What is an atom?

An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.

The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.

Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.

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How many moles of precipitate will be formed when 100.0 mL of 0.200 M NaBr is reacted with excess Pb(NO₃)₂ in the following chemical reaction?

2 NaBr (aq) + Pb(NO₃)₂ (aq) → PbBr₂ (s) + 2 NaNO₃ (aq)

Answers

Answer : The number of moles of precipitate, [tex]PbBr_2[/tex] formed will be 0.01 moles.

Explanation : Given,

Concentration of NaBr = 0.200 M

Volume of solution = 100.0 mL = 0.1 L      (1 L = 1000 mL)

First we have to calculate the moles of NaBr.

[tex]\text{Moles of NaBr}=\text{Concentration of NaBr}\times \text{Volume of solution in L}[/tex]

[tex]\text{Moles of NaBr}=0.200M\times 0.1L=0.02mol[/tex]

Now we have to calculate the moles of precipitate, [tex]PbBr_2[/tex] formed.

The balanced chemical reaction is:

[tex]2NaBr(aq)+Pb(NO_3)_2(aq)\rightarrow PbBr_2(s)+2NaNO_3(aq)[/tex]

From the balanced chemical reaction we conclude that:

As, 2 moles of NaBr react to give 1 mole of [tex]PbBr_2[/tex]

So, 0.02 moles of NaBr react to give [tex]\frac{0.02}{2}=0.01[/tex] mole of [tex]PbBr_2[/tex]

Therefore, the number of moles of precipitate, [tex]PbBr_2[/tex] formed will be 0.01 moles.

The number of mole of the precipitate (i.e PbBr₂) formed when 100 mL of 0.2 M NaBr react with excess Pb(NO₃)₂ is 0.01 mole

We'll begin by calculating the number of mole of NaBr in 100 mL of 0.2 M NaBr solution. This can be obtained as follow:

Volume = 100 mL = 100 / 1000 = 0.1 L

Molarity of NaBr = 0.2 M

Mole of NaBr =?

Mole = Molarity x Volume

Mole of NaBr = 0.2 × 0.1

Mole of NaBr = 0.02 mole

Finally, we shall determine the number of mole of the precipitate (i.e PbBr₂) produced from the reaction. This can be obtained as follow:

2NaBr(aq) + Pb(NO₃)₂(aq) → PbBr₂(s) + 2NaNO₃ (aq)

From the balanced equation above,

2 moles of NaBr reacted to produce 1 mole of PbBr₂.

Therefore,

0.02 mole of NaBr will react to produce = [tex]\frac{0.02}{2} \\\\[/tex] = 0.01 mole of PbBr₂.

Thus, the number of mole of the precipitate (i.e PbBr₂) produced from the reaction is 0.01 mole

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