S1.1 - Introduction to the Particulate Nature of Matter

Which of the following is an example of a mixture?

• A.$\hspace{1em}$ Sucrose

• B.$\hspace{1em}$ Distilled water

• C.$\hspace{1em}$ Seawater

• D.$\hspace{1em}$ Sodium chloride

Which of the following is a characteristic of liquids?

• A.$\hspace{1em}$ Their particles vibrate about fixed positions

• B.$\hspace{1em}$ They can be compressed easily

• C.$\hspace{1em}$ They take up the shape of the container they are in

• D.$\hspace{1em}$ The particles move freely and quickly in all directions

Which of the following methods is used to separate a solid from a liquid in a heterogeneous mixture?

• A.$\hspace{1em}$ Distillation

• B.$\hspace{1em}$ Filtration

• C.$\hspace{1em}$ Crystallisation

• D.$\hspace{1em}$ Sublimation

A liquid has a boiling point of $-185 ^\circ\mathrm{C}$. What is this temperature in Kelvin?

• A.$\hspace{1em}$ 88 K

• B.$\hspace{1em}$ $-88$ K

• C.$\hspace{1em}$ 458 K

• D.$\hspace{1em}$ $-458$ K

Which of the following requires a chemical reaction to be separated into simpler substances?

• A.$\hspace{1.em}$Homogeneous mixtures

• B.$\hspace{1.em}$Heterogeneous mixtures

• C.$\hspace{1.em}$Alloys

• D.$\hspace{1.em}$Compounds

Which of the following correctly classifies $\ce{S8}$ and water?

• A.$\hspace{1.em}\ce{S8}$ and water are both compounds.

• B.$\hspace{1.em}\ce{S8}$ and water are both elements.

• C.$\hspace{1.em}\ce{S8}$ is a compound, and water is an element.

• D.$\hspace{1.em}\ce{S8}$ is an element, and water is a compound.

Which of the following statements correctly describes a compound?

• I.$\hspace{1.em}$A compound can be physically separated into simpler substances

• II.$\hspace{0.7em}$In a pure compound, the boiling point, melting point and solubility are uniform.

• III.$\hspace{0.4em}$Each compound has a fixed chemical formula in which the subscripts remain constant.

• A.$\hspace{1.em}$I and II only

• B.$\hspace{1.em}$I and III only

• C.$\hspace{1.em}$II and III only

• D.$\hspace{1.em}$I, II and III

In the following paper chromatogram using water as the solvent, which component of the mixture (1 or 2) has the greatest affinity for the mobile phase, and what is the identity of the mobile phase?

• A. $\hspace{1em}$ 1; water

• B. $\hspace{1em}$ 1; paper

• C. $\hspace{1em}$ 2; water

• D. $\hspace{1em}$ 2; paper

[Maximum marks: 7]

Crude oil (also known as petroleum) is a homogeneous mixture of volatile liquid hydrocarbons. Before it can be used, it must be refined to separate it into simpler, more useful mixtures.

1. Describe a homogeneous mixture. [1]
   

2. Contrast the microscopic structure and behavior of liquids and gases using the kinetic molecular theory. [2]
   

3. State the physical property of the components of crude oil that allows them to be separated by fractional distillation. [1]
   

4. Kerosene, a fuel used in aviation, is one of the fractions obtained from crude oil. $\newline \ \newline$

   1. Kerosene has a boiling point of 240.00°C. Convert this temperature to Kelvin using Section 1 of the IB Chemistry Data Booklet. [1]
      

   2. Explain, using the kinetic molecular theory, why kerosene vaporizes when heated. [2]
      

Which of the following is a mixture?

• I. $\hspace{1em}$ Solder
  II. $\hspace{0.5em}$ Ammonia
  III. $\hspace{0.3em}$ Seawater

• A. $\hspace{1em}$ I only

• B. $\hspace{1em}$ I and II only

• C. $\hspace{1em}$ I, II, and III

• D. $\hspace{1em}$ I and III only

Which of the following statements is correct about liquids?

• A. $\hspace{1em}$ They can be compressed and undergo an endothermic process to vaporize

• B. $\hspace{1em}$ They cannot be compressed and undergo an endothermic process to vaporize

• C. $\hspace{1em}$ They can be compressed and undergo an exothermic process to vaporize

• D. $\hspace{1em}$ They cannot be compressed and undergo an exothermic process to vaporize

[Maximum mark: 6]

Carbon undergoes combustion in the presence of oxygen, as shown below.

$\ce{C (s) + O2 (g) → CO2 (g)}$

Solid carbon dioxide, known as dry ice, is used in vaccine cooling and preserving blood and tissue samples.

1. Complete the table below by stating the term element, compound, or mixture to classify reactants and products. [1]
   

• $\ce{C (s)}$	$\ce{O2 (g)}$	$\ce{CO2(g)}$
  		$\hspace{1em}$

2. Gaseous carbon dioxide can be converted into dry ice. State the name of this process. [1]
   

3. Evaluate the benefits of dry ice in vaccine cooling. [2]
   

4. Dry air is composed of nitrogen, oxygen, carbon dioxide, and other gases.
   Comment on the statement below:

¨Dry air is a homogeneous mixture.¨ [2]

The heating curve of a substance is given below.

$\footnotesize{\textrm{[© Revision Village 2023]}}$

Which statement(s) below is(are) correct?

• I.	Y is the melting point
  II.	Through MN, an input of energy increases the energy of the solid
  III.	Through NO, the liquid and solid states coexist

• A. $\hspace{1em}$ I and II only

• B. $\hspace{1em}$ I, II, and III

• C. $\hspace{1em}$ II and III only

• D. $\hspace{1em}$ II only

Sugar must be recovered from a solution of sugar and ethanol.

$\textit{Hint: Ethanol is highly flammable with a boiling point of 78°C.}$

Which statement(s) below is(are) correct?

• I.	Evaporation with a Bunsen burner is an appropriate technique
  II.	A hot water bath (above 78°C) can be used with an evaporating basin containing the mixture as a proper technique
  III.	Filtration is a safe and appropriate technique for this purpose

• A. $\hspace{1em}$ I only

• B. $\hspace{1em}$ II only

• C. $\hspace{1em}$ III only

• D. $\hspace{1em}$ I and II only

Which statement(s) is(are) correct about the condensation of water?

• I.	It is the reverse of sublimation.
  II.	It is exothermic.
  III.	$\ce{H2O}$ molecules arrange in a fixed shape.

• A. $\hspace{1em}$ I only

• B. $\hspace{1em}$ II only

• C. $\hspace{1em}$ III only

• D. $\hspace{1em}$ I, II, and III

Consider the heating curve of ethanol below.

[© Revision Village 2023]

Which statement is correct about ethanol?

• A. $\hspace{1em}$ Condensation takes longer than freezing as more heat is needed for this physical change

• B. $\hspace{1em}$ Condensation takes longer than freezing as more heat must be removed for this physical change

• C. $\hspace{1em}$ At 78 $\text{\textdegree}C$ sublimation occurs

• D. $\hspace{1em}$ At $-$114 $\text{\textdegree}C$ deposition occurs

Which of the following correctly describes the properties of a homogeneous mixture?

• A.$\hspace{1.em}$The physical properties are uniform and the chemical properties of its components remain unchanged.

• B.$\hspace{1.em}$The physical and chemical properties are those of its most abundant component.

• C.$\hspace{1.em}$The physical and chemical properties are an average of the properties of its components.

• D.$\hspace{1.em}$The physical properties vary throughout the sample, and its components do not retain their chemical properties.

[Maximum mark: 7]

Some plant pigments were analyzed through paper chromatography. Standards A, B, C, and D have been used against the pigments.

$\footnotesize{\textrm{[© Revision Village 2023. Created with Chemix (https://chemix.org)]}}$

A group of students analyzed the results. Some of their hypothesis are listed below.

Mariana´s hypothesis: Plant Z contains pigments B and C, and it has been proven to be a mixture of three components.

Hiba´s hypothesis: Plant Y presents pigments A and D. All three plants are made of a mixture of pigments.

Priya´s hypothesis: Plant X has many colored components. The red component is the one with the lowest retention factor.

1. Comment on each hypothesis and determine its validity. [3]
   

2. Calculate the retention factor of the red spot in standard A. [1]
   

3. Identify the standard with the lowest affinity for the solvent used in the paper chromatography. Explain your reasoning. [2]
   

4. Suggest a limitation of the paper chromatography described as a separating technique. [1]
   

A mixture is composed of wood chips, water, and sodium chloride. Which sequence of techniques could be used to isolate the wood chips and the sodium chloride separately?

• A. $\hspace{1em}$ Evaporation followed by paper chromatography

• B. $\hspace{1em}$ Filtration followed by paper chromatography

• C. $\hspace{1em}$ Evaporation followed by solvation

• D. $\hspace{1em}$ Filtration followed by evaporation

[Maximum mark: 11]

The melting point of benzene is 5.5$°C$, and its boiling point is 80.1$°C$.

1. Draw the heating curve for benzene from -10$°C$ to 110$°C.$ [3]
   

2. State the state of matter of benzene at -6.0$°C.$ [1]
   

3. Describe the arrangement of benzene molecules at 50.0$°C.$ [2]
   

4. 5.00 $g$ of $\ce{NaCl}$ is added to 100 $cm^3$ of benzene. The salt is insoluble in the solvent.

   (i) Determine the type of mixture formed. [1]
   

   (ii) Suggest a technique that can be applied to separate and recover benzene and sodium chloride. Sketch a labeled diagram to show how the separation will take place. [4]
   

[Maximum mark: 7]

The diagram below represents the heating of ice starting at $-20\, {}^\circ \mathrm{C}$.

1. Complete the table. [5]
   

   Segment number	What phase(s) is/are present?	What is happening at the particle level?	What phase change, if any, is taking place?
   1
   2
   3
   4
   5

2. Give the melting point of the substance. [1]
   

3. Identify the state of particles at $110\, {}^\circ\mathrm{C}$. [1]
   

[Maximum mark: 10]

Biological dyes contaminated a local pond. These dyes are known to be soluble solids. A sample of the polluted pond water was collected for separation and further identification of the dyes to determine how best to remediate the area.

1. State whether this mixture is homogeneous or heterogeneous, explaining your answer. [2]
   

2. State the technique that could be used to remove the wood chips, algae, and plant matter from the mixture. [1]
   

3. State the technique that could be used to isolate the dissolved solids (salts, dyes, etc) from the water. [1]
   

4. State the technique that could be used to separate the salts from the dyes. [1]
   

5. Explain the properties of the substances that enable their separation in question (d). [2]
   

6. Once the dyes have been separated from the remainder of the sample, paper chromatography could be used to determine how many dyes are present. State the identity of the stationary phase and an example of a mobile phase. [1]
   

7. From the following paper chromatogram, state which dye (A or B) has a greater affinity for the mobile, describing the evidence to support this answer. [2]
   

A scientist wants to analyze the components of an ink sample. The ink is first dissolved in an organic solvent and separated into its components using paper chromatography. The solvent is then distilled to remove impurities and be reused.

Which of the following properties enable these separation techniques to be effective?

$\mbox{}\\[-15pts]$

A dye has been contaminated with another substance, and this dye undergoes recrystallization in an attempt to remove the contaminant.
Which of the paper chromatograms below (A, B, C, or D) indicates that the recrystallization successfully removed the contaminant?

Each chromatogram contains a before recrystallization (1) and after recrystallization (2).

Paper chromatography is a technique that can be used to separate which of the following?

• A.$\hspace{1em}$ A liquid and an insoluble solid

• B.$\hspace{1em}$ Soluble solids

• C.$\hspace{1em}$ A solid and an insoluble liquid

• D.$\hspace{1em}$ Insoluble solids

A mixture of 100 $g$ of sand, 1.00 $g$ of sodium chloride, 200 $cm^3$ of water, and 2.00 $g$ of iron fillings must be separated. All the components are expected to be recovered.
Which sequence of steps would work for this purpose?

• A. $\hspace{1em}$ Filtration, evaporation of the filtrate, and use of a magnet with the residue

• B. $\hspace{1em}$ Filtration, evaporation of the residue, and use of a magnet with the filtrate

• C. $\hspace{1em}$ Filtration, simple distillation of the filtrate and use of a magnet with the residue

• D. $\hspace{1em}$ Filtration, simple distillation of the residue and use of a magnet with the filtrate

The boiling point of propan-2-ol is 82$°C$. Which statement(s) below is(are) correct?

• I.	Evaporation of propan-2-ol can occur at 80$°C$
  II.	At 82$°C$ condensation of propan-2-ol can occur
  III.	Propan-2-ol at 100$°C$ presents particles close together and randomly arranged

• A. $\hspace{1em}$ I only

• B. $\hspace{1em}$ II only

• C. $\hspace{1em}$ I and II only

• D. $\hspace{1em}$ III only

A solution of isopropyl alcohol and propan-1-ol must be separated. The structural formulas of these are given below.

$\footnotesize{\textrm{[© Revision Village 2023]}}$

Hint: Substituted hydrocarbons present weaker intermolecular forces.

Which statement(s) is(are) correct?

• I.	Distillation allows the separation of the components of the mixture
  II.	A condenser, a thermometer, and an evaporating basin are needed for distillation
  III.	If distillation is applied, the distillate is isopropyl alcohol

• A. $\hspace{1em}$ I and II only

• B. $\hspace{1em}$ I and III only

• C. $\hspace{1em}$ III only

• D. $\hspace{1em}$ II only

[Maximum mark: 3]

The table below shows the data gathered by a chemist regarding substances A, B, and C. Using the data given, discuss which is a pure substance or a mixture. If the substance is a pure substance, determine whether it is an element or a compound.

Substance	Appearance	Melting point	Observed property
A	White crystalline solid	$801\,{}^\circ\mathrm{C}$	In aqueous solution, it reacts with silver nitrate forming a precipitate of silver chloride
B	Silver metallic appearance	$660\,{}^\circ\mathrm{C}$	Reacts with oxygen forming an oxide
C	Fine white crystalline solid	$186\,{}^\circ\mathrm{C}$ - $800\,{}^\circ\mathrm{C}$	Readily dissolves in water

A gas is placed in a sealed rigid container and heated. What happens to the gas particles according to the kinetic molecular theory?

• A.$\hspace{1.em}$They move faster and collide more frequently with each other, but the pressure remains constant.

• B.$\hspace{1.em}$They gain kinetic energy and move faster, increasing collisions with the container walls, which increases pressure.

• C.$\hspace{1.em}$They expand within the container, increasing the density of the gas.

• D.$\hspace{1.em}$They gain kinetic energy, but temperature remains constant as intermolecular forces are overcome.

A chemist wants to purify a solid organic compound contaminated with small amounts of a soluble impurity. Which technique is most appropriate?

• A.$\hspace{1.em}$Evaporation

• B.$\hspace{1.em}$Distillation

• C.$\hspace{1.em}$Recrystallization

• D.$\hspace{1.em}$Filtration

A sample of solid iodine is placed in a sealed flask. The sample is heated gently. After a few minutes, the solid disappears, and a purple vapor is visible in the container. When the sample is cooled, solid iodine is again visible on the walls of the flask.

Which of the following best explains this observation?

• A.$\hspace{1.em}$During heating, iodine particles absorb energy and evaporate; during cooling, iodine particles release energy and condense.

• B.$\hspace{1.em}$During heating, iodine particles absorb energy and condense, during cooling, iodine particles release energy and evaporate.

• C.$\hspace{1.em}$During heating, iodine particles absorb energy and sublimate; during cooling, iodine particles release energy and undergo deposition.

• D.$\hspace{1.em}$During heating, iodine particles absorb energy and undergo deposition; during cooling, iodine particles release energy and sublime.

Which statement correctly describes the behavior of particles during the phase change from liquid to gas at the boiling point?

• A.$\hspace{1.em}$Particles remain in the liquid phase until the temperature exceeds the boiling point.

• B.$\hspace{1.em}$Particles absorb energy to overcome intermolecular forces, causing a continuous rise in temperature.

• C.$\hspace{1.em}$Particles absorb energy to overcome intermolecular forces, but the temperature remains constant.

• D.$\hspace{1.em}$Particles experience no change in energy while transitioning from liquid to gas.

A sample of ethanol is placed in an open container. Over time, the volume of the liquid decreased, even though the temperature remained constant at 25$^\circ$C.

Select the statement that best describes this phenomenon

• A.$\hspace{1.em}$Ethanol molecules at the surface vaporized at a temperature below boiling point.

• B.$\hspace{1.em}$Ethanol intermolecular forces are weaker at the surface, leading to vaporization.

• C.$\hspace{1.em}$Ethanol molecules reached the boiling point and vaporized.

• D.$\hspace{1.em}$Ethanol molecules underwent a decrease in pressure, leading to vaporization.

During a calorimetry experiment, a student recorded the initial and final temperature of a sample in the table below:

	Temperature /$^\circ$C$\\$ $\mathbf\pm 0.5^\circ$C
$\ \ \ \ \$Initial$\ \ \ \ \$	18.0
Final	72.0

What is the temperature change in Kelvin, including its uncertainty?

• A.$\hspace{1.em}327.0 \pm 1.0 \textrm{\ K}$

• B.$\hspace{1.em}327.0 \pm0.5 \textrm{\ K}$

• C.$\hspace{1.em}54.0 \pm 1.0 \textrm{\ K}$

• D.$\hspace{1.em}54.0 \pm 0.5 \textrm{\ K}$

A mixture is investigated through paper chromatography, comparing it with standards X, Y, and Z. The development of the chromatograph allows the interpretation of the results shown below.

$\footnotesize{\textrm{[© Revision Village 2023.Created with Chemix (https://chemix.org)]}}$

Which statement(s) is(are) correct?

• I.	X and Y are present in the mixture
  II.	Z is not present in the mixture
  III.	The mixture must have been made with five components only

• A. $\hspace{1em}$ I only

• B. $\hspace{1em}$ I and II only

• C. $\hspace{1em}$ I, II, and III

• D. $\hspace{1em}$ II and III only