Can the Simple Test for Carbon Dioxide be Modified to Quantitatively Measure the Amount of Carbon Dioxide Present in a Mixture of Gass?
Abstraction
Carbon dioxide is a “a colorless, odorless, tasteless gas that is about one and one-half times every bit dense as air under ordinary conditions of temperature and force per unit area. ” [ 1 ] It has many features that make it an of import gas with many utilizations ( i.e. used in fire asphyxiators, carbonated drinks, etc ) . This probe tried to analyze the effectivity of utilizing a simple quantitative trial which helps find the presence of C dioxide in a mixture of gases to quantify the sum of C dioxide in such mixture.
Three experiments were carried out to decide the research job, viz. : ( 1 ) readying of C dioxide ; ( 2 ) public presentation of the qualitative trial for the presence of C dioxide ; and ( 3 ) titration of the precipitate with hydrochloric acid.
Consequences of the experiment showed that the sum of C dioxide can be calculated stoichiometrically in readying of C dioxide, but the same can non be done by set abouting neither the qualitative trial nor the titration experiment.
This probe finds that the simple trial for the presence of C dioxide can non be modified to quantitatively measure the sum of C dioxide.
Table of Contentss
1. Introduction
1.1 Background Information
1.2 Simple Test for Carbon Dioxide
2. Experimental Method
2.1 Introduction
2.2 Apparatus
2.3 Methods
3.0 Consequences and Discussion
3.1 Consequences and Discussion of the Three Methods used in the Survey
3.2 Improvement of the Experiments
4.0 Decisions
5.0 Bibliography
Table 1 Consequences Obtained in the Preparation of Carbon Dioxide
Table 2 Volume of CaCO3 used and CO2 produced in milliliter
Figure 1 Pressure-Temperature stage diagram for CO2.
Figure 2 Carbon Dioxide Gas Test
There is no standard experiment for mensurating the sum of C dioxide nowadays in a mixture of gases in any text edition used for Chemistry in the IB. A by and large accepted qualitative trial throughout many course of studies is where the mixture of gases is bubbled through limewater ( concentrated Ca hydroxide solution ) and if C dioxide is present ; it reacts with the hydrated oxide bring forthing Ca carbonate precipitate that turns the H2O “milky” . [ 2 ]
There is a famine in available literature that supports the effectivity of the qualitative trial for the presence of C dioxide in determining its measure in a mixture of gases. Hence, this probe will seek to research the possibility of utilizing such trial to quantify the sum of C dioxide in a mixture or solution in add-on to finding the presence of the gas. This probe will therefore attempt to reply the undermentioned research inquiry:
In order to supply an reply to this research inquiry, this probe will supply some background information sing C dioxide by discoursing its belongingss and features every bit good as by depicting the qualitative trial for C dioxide. Following, it will explicate the methods used in this probe. Then it will show the consequences of the experiments conducted. Finally, it will show the decisions derived from the scrutiny of the facts presented.
1.1 Background Information
Carbon dioxide, which is a colorless gas at 25EsC and at a force per unit area of 1 standard pressures, condenses to go a white crystalline substance when chilled to -78.5EsC at the same force per unit area. “If the force per unit area is increased to 5.2 standard pressure, the crystalline substance thaws to a liquid at -56.6Es C. Under ordinary force per unit area, so, the solid substance is changed straight to a gas. This belongings has made solid C dioxide ( dry ice ) popular as a refrigerating agent” . [ 3 ] Figure 1 below shows the Pressure-Temperature stage diagram for CO2.
Figure 1 Pressure-Temperature stage diagram for CO2. [ 4 ]
Figure 2 below shows the Lewis diagram of the CO2molecule whereby the C atom at the Centre has no lone negatron brace. “The C and both O are bonded through dual bonds which counts as “ two negatron braces ” . Hence the molecule has two negatron braces and is linear.” [ 5 ] Harmonizing to Manaa [ 6 ] , this additive molecular geometry of CO2is what makes it exhibit the physical features described supra. Such that, at ambient temperatures, it crystallizes into three-dimensional ( Pa-3 ) stage I known as ‘dry ice’ at around 1.5 GPa and 4500 K.” [ 7 ]
Figure 2 Linear Molecular Geometry of Carbon Dioxide [ 8 ]
Furthermore, because of the physical and chemical belongingss of CO2, assorted of import utilizations of the compound have been discovered. Carbon dioxide is an of import ingredient in doing carbonated drinks, owing to its ability to organize an acid when reacted with softdrinks since it is “the acerb anhydride of carbonaceous acid.” [ 9 ] During the production of carbonated drinks, “carbonated H2O is charged with C dioxide under a force per unit area 3 or 4 atm.” [ 10 ] Solid CO2or ‘dry ice’ “is used as a refrigerant because it has the advantage of non runing into a liquid but sublimes and in the procedure absorbs 3 times every bit much heat per gm as ice.” [ 11 ] Additionally, CO2is an of import constituent of fire asphyxiators because it is one and a half times heavier than air and “does non back up ordinary combustion.” [ 12 ]
The solubility of CO2in H2O is affected by temperature, as it becomes less soluble in H2O at higher temperatures. For illustration, “one vol. dissolves in 0.6 vol. H2O at O°C, in 13 vols. H2O at 25°C ; one gm in 300 milliliter. H2O at O°C, in 700 milliliter. H2O at 25Es C.” [ 13 ] Thus, the solubility of CO2in H2O follows Henry’s Law and shows a additive relationship with the partial force per unit area of CO2in the gas stage ( 0.03 % for CO2= 0.23 mmHg ) . [ 14 ] ” Under normal conditions, the solubility of CO2is 0.4 milligram a„“-1at 30Es C, 0.5mg a„“-1at 20Es C and 1mg a„“-1at 0Es C.” [ 15 ]
However, “when C dioxide dissolves in H2O, some of it reacts to organize carbonaceous acid: Carbon monoxide2+ H2O > H2Carbon monoxide3.” [ 16 ] Figure 3 below shows the molecular construction of carbonaceous acid, which is diprotic, whereby it can organize both a normal salt and an acerb salt. “The normal salt contains the carbonate ion, CO3—, and the acid salt contains the H carbonate ion, HCO2–.[ 17 ]
Figure 3Molecular Structure of Carbonic Acid [ 18 ]
Carbonates such as limestone ( Ca CO3) are indissoluble in H2O. [ 19 ] Thus, the rate of precipitation is little in the cold, greater in the hot, whence the demand to heat in order to precipitate the carbonates.” [ 20 ] “ Carbonates besides give off C dioxide when treated with dilute acids, e.g. , hydrochloric acid. ” [ 21 ] “The carbonate ion behaves as a Bronsted base:
CaCO3 (s) + 2 H+ (aq) > Ca2+ (aq) + H2CO3 (aq)
The aqueous carbonaceous acid dissociates, bring forthing C dioxide gas:
H2CO3 (aq) > H2O (cubic decimeter) + CO2 (g) .”[ 22 ]
1.2 Simple Test for Carbon Dioxide
A simple process for the production of C dioxide is based on the reaction of Ca carbonate and hydrochloric acid to bring forth C dioxide. The general chemical equation involved is as follows:
CaCO3 ( s )+ 2HCl( aq )== & gt ;CaCl2 ( aq )+ H2Oxygen( cubic decimeter )+ CO2 ( g )
whereby solid Ca carbonate is assorted with hydrochloric acerb solution to bring forth aqueous Ca chloride, H2O and C dioxide gas.
On the other manus, to find the presence of CO2 ( g ) , a trial which consists of go throughing it through limewater ( CaOH )2[ 23 ],which “is a solution of Ca hydrated oxide in water” [ 24 ] can be carried out. The reactions involved in this trial are as follows:
Carbon monoxide2(aq) + H2O (cubic decimeter)>Hydrogen2Carbon monoxide3(aq)[ 25 ] [ 1 ]
When C dioxide dissolves in H2O, carbonaceous acid is produced ( equation 1 ) , whereby “an equilibrium is established between the dissolved CO2 and H2CO3, carbonaceous acid.” [ 26 ]
Ca ( OH )2 ( aq )+Carbon monoxide2 ( g )arrowCaCO3 ( s )+Hydrogen2Oxygen( cubic decimeter )[ 2 ] [ 27 ]
It is so passed through limewater which “neutralizes the carbonaceous acid and carbonate ion is formed. Calcium carbonate is indissoluble and precipitates” [ 28 ] ( equation 2 ) . If C dioxide gas ( CO2 ( g )) is “bubbled through it, a solid precipitate of Ca carbonate is formed. Calcium carbonate is chalk or limestone, and it is this that makes the lime H2O cloudy.” [ 29 ]
CaCO3 ( s )+ 2 H+ (aq) > Ca2+ (aq) + H2Carbon monoxide3(aq) [ 3]
“Although ‘insoluble’ in H2O, Ca carbonate dissolves in acidic solutions. The carbonate ion behaves as a Bronsted base { equation 3 ) .” [ 30 ] However, without utilizing acidic solutions, “continued passing of CO2into the solution will unclutter the cloudy status because the indissoluble CaCO3 becomes soluble Ca carbonate [ … ] .” [ 31 ] This is illustrated in the followers ( equation 4 ) :
CaCO3 ( s )+ H2O + CO2 ( g )> Ca2+( HCO3)2–[ 4 ]
Therefore, Ca carbonate combines with H2O and C dioxide to bring forth a solution of Ca H carbonate [ 32 ] . Both equations 3 and 4 would ensue to the dissociation of carbonaceous acid to bring forth H2O and C dioxide gas ( equation 5 ) . [ 33 ]
Hydrogen2CO3 (aq) > H2O (cubic decimeter) + CO2 (g) [ 5 ]
Figure 2 below shows the cloudy H2O in the trial tubing bespeaking the presence of C dioxide gas.
Figure 2 Carbon Dioxide Gas Test [ 34 ]
2.1 Introduction
Overall, this survey utilized two methods to find the possibility of modifying the simple C trial to quantitatively measure the sum of C dioxide in a mixture of gases. The simple C trial which was done through go throughing the C dioxide through limewater consisted of the undermentioned reaction: [ 35 ]
Carbon monoxide2(aq) + H2O (cubic decimeter)>Hydrogen2Carbon monoxide3(aq)
This simple trial for the presence of C dioxide in a mixture of gases was based on the premiss that if C dioxide is so present in the mixture of gases, “the limewater will turn “cloudy because of the formation of a white precipitate of a finely divided Ca carbonate” [ 36 ] ( CaCO3) . The equation below shows the reaction involved in the trial.
Ca ( OH )2 ( aq )+Carbon monoxide2 ( g )arrowCaCO3 ( s )+Hydrogen2Oxygen( cubic decimeter )
Another method ( Method 1 ) was undertaken in order to quantitatively find the sum of C dioxide gas nowadays in the mixture. This 2nd method produced the undermentioned reaction:
CaCO3 ( s )+ 2HCl( aq )== & gt ;CaCl2 ( aq )+ H2Oxygen( cubic decimeter )+ CO2 ( g )
Still another experiment ( Method 2 ) was carried out to find the sum of C dioxide gas nowadays in the mixture through titrating Ca H carbonate solution with hydrochloric acid and used Phenolphthalein as index. The reaction involved is as follows:
CaCO3+ 2HCli?Carbon monoxide2+ CaCl2+ H2Oxygen
The first method that was carried out was the readying of C dioxide, followed by the simple C dioxide trial and so by titration to quantify the C dioxide produced.
In drumhead, Method 1 investigated the mass addition of the solution due to the formation of the precipitate. Method 2 used the solution with the precipitate and titrated it against hydrochloric acid utilizing phenolphthalein index. Furthermore, the above, carry comparatively simple processs and therefore can be easy repeated when accompanied with instructions. However, like any experiment conducted in a school research lab, or in fact in any research lab, they carry mistakes due to the restrictions of the setup used for measurement and other general restrictions such as gases lost during experiment. However through repeat of the method, the random mistakes can be spotted, and considered as anomalousnesss.
2.2 Apparatus
This survey used the undermentioned stuffs and equipment for the experimental methods performed:
A. For the readying of C dioxide and the finding of the presence of C dioxide:
Calcium Carbonate
50 milliliter of 1M of Hydrochloric
1 gm of Ca carbonate
Electronic Balance
Air Pump
Volumetric Flask
Tubing
B. For Titration:
Burettes
Pipets
Retort base
Dropper
Phenolphthalein index
Hydrochloric acid
2.3 Methods
A. Fixing Carbon dioxide
To fix the C dioxide a known sum of hydrochloric acid will be added to a known sum of Ca carbonate. This portion of the experiment will transport out as follows:
Measure out sum of CaCO3needed ( the sum are detailed in the Methods )
Measure out 25cm3of HCl with a concentration that ensures that HCl is in surplus. ( 1M solution was used. )
Set up setup as image below.
CaCO3 ( s )+ 2HCl( aq )== & gt ;CaCl2 ( aq )+ H2Oxygen( cubic decimeter )+ CO2 ( g )
B. Simple Carbon Dioxide Test
If utilizing Calcium Hydroxide:
Fix a standard solution by fade outing 0.99g to 1.00g==== Ca ( OH )2in 250ml to give a 0.1M solution
Set up the undermentioned system as shown below:
First pump air through limewater, to take the Carbon dioxide, so pump through the solution to saturate it with C dioxide free air. This will drive off the C dioxide from the Ca carbonate that will be used for the measuring.
Set up setup as shown below for the production of C dioxide gas.
Measure the mass of the solution and flask with gum elastic spile.
Produce Carbon dioxide in the conelike flask.
Let the C dioxide bubble through the hydrated oxide until the no farther bubbles are formed.
Measure the mass of the solution and flask with gum elastic spile ; cipher the difference from old measuring.
From the dry mass formed the sum of C dioxide can be deducted.
The expression for the reaction:
Ca ( OH )2( aq )+ CO2( g )> CaCO3( s )+ H2Oxygen( cubic decimeter )
The sum of C dioxide nowadays can be determined utilizing stoichiometry as the sum of hydrated oxide is known, and the sum of carbonate is measured.
C. Titration
This is titrating the Ca carbonate/hydroxide solution ( whatever is left after the bubbling ) against hydrochloric acid utilizing Phenolphthalein index. I will compose this method. This failed…because the measures are excessively little (Limewater is 0.02M of Ca carbonate….Therefore through computation utilizing 10 milliliter of limewater the potency is merely 0.0088g )
3.1 Consequences and Discussion of the Three Methods used in the Survey
A. Preparation of Carbon Dioxide
In the readying of C dioxide, 1 gm of Ca carbonate in 50 milliliter of 1M of Hydrochloric acid was used to bring forth CO2. The tabular array below shows the consequences obtained. Table 1 nowadayss the consequences obtained in milliliter of merchandise.
Table 1 Consequences Obtained in the Preparation of Carbon Dioxide
Run figure
Initial Measurement in milliliter
Concluding Measurement in milliliter
1
77.69
80.04
2
79.39
79.36
3
84.42
84.30
The balanced equation for this reaction is:
CaCO3 ( s )+ 2HCl( aq )== & gt ;CaCl2 ( aq )+ H2Oxygen( cubic decimeter )+ CO2 ( g )
Furthermore, the equation is besides stoichiometrically balanced since:
CaCO3i? Ca+++ CO32-
2HCl i? 2H++ 2Cl?
Calcium+++ 2Cl–i? CaCl2
Carbon monoxide32-i? CO2+ O2-
2H++ O2– i? H2Oxygen
In the balanced chemical equation, 1 mole of CaCO3 give1 mole of CO2. That means 100 milligram of CaCO3 will give out 44 milligram of CO2.Harmonizing to Mascetta, “since the denseness of the gas is normally given in g/L of gas at STP, we can utilize the molar volume to molar mass “to calculate for the molar mass of CO2given the weight of Calcium Carbonate ( CaCO3) when it is reacted with a known molar volume of hydrochloric acid ( HCl ) .” [ 37 ]
Therefore, the undermentioned computations were undertaken:
A. Run 1:
Volume of CaCO3 used = 80.04 – 77.64
= 2.40 milliliter
Volume of CO2 produced = 0.44 Ten 2.40
= 1.056 milliliter
B. Run 2.
Volume of CaCO3 used = 79.39 – 79.36
= 0.03 milliliter
Volume of CO2 produced = 0.44 Ten 0.03
= 0.0132 milliliter
C. Run 3:
Volume of CaCO3 used = 84.42 – 84.30
= 0.12 milliliter
Volume of CO2 produced = 0.44 Ten 0.12
= 0.0528 milliliter
Table 2 presents the deliberate values of CaCO3 used and CO2 produced in milliliter.
Table 2 Volume of CaCO3 used and CO2 produced in milliliter
Run
Volume of CaCO3 used in milliliter
Volume of CO2 produced in milliliter
1
2.40
1.056
2
0.03
0.0132
3
0.12
0.0528
B. Simple Test for the Presence of Carbon Dioxide Gas in Gas Mixtures
When the solution of the prepared C dioxide was passed through the limewater solution and it turned cloudy. The chemical equation for this reaction is:
Ca ( OH )2( aq )+ CO2( g )> CaCO3( s )+ H2Oxygen( cubic decimeter )
C. Titration
In this method, the solution with the precipitate in Method B was used. It was titrated it against hydrochloric acid utilizing phenolphthalein index.
The balanced equation for this reaction is:
CaCO3+ 2HCli?Carbon monoxide2+ CaCl2+ H2Oxygen
Therefore, the mass of the C produced can be calculated utilizing the undermentioned stairss:
Calculate mass of CaCO3in g/Atomic Weight of CaCO3= x M
Number of moles of CaCO3= x * ( molecules of CO2/molecules of CaCO3)
Mass of CO2= figure of moles * atomic weight of CO2
However, the solution ( that should hold the dissolved CO2 – Ca carbonate ) did non turn from colorless to tap. No affair how much HCl was added ; therefore it could non be titrated. Therefore, the sum of C dioxide produced was non determined. In this peculiar experiment, the failure in the finding of the sum of C dioxide produced is mostly based on the nature of titration itself. Titration is non performed with precipitates. Titration is the “gradual add-on of an acidic solution to a basic solution or frailty versa [ … ] ; titrations are used to find the concentration of acids or bases in solution. For illustration, a given volume of a solution of unknown sourness may be titrated with a base of known concentration until complete neutralisation has occurred. This point is called the equality point and is by and large determined by detecting a colour alteration in an added index such as phenolphthalein.” [ 38 ] Therefore, the precipitate in the signifier of Ca carbonate ( CaCO3( s )) can non be titrated with HCl.
3.2 Improvement of the Experiments
The aforesaid three experiments all carry obvious mistakes, in add-on to the systematic mistakes, the mistakes due to truth of the steps, and the loss of some gas when reassigning it from glasswork to another. Some of the ways to better the truth of the experimental consequences include the consideration of the undermentioned salient points:
Calcium hydrated oxide will absorb C dioxide from the environment. This can be minimized by either pumping saturated air through the Ba and Ca hydrated oxide to drive off C dioxide, or it can be subtracted from the consequence by mensurating the sum of C dioxide absorbed from the environment during the clip of use by puting up a control experiment.
As C dioxide is introduced into the limewater it will respond to organize Ca carbonate [ CO2 (aq) + H2O (cubic decimeter) > H2CO3 (aq) ] which, nevertheless, will besides organize carbonaceous acid [ CaCO3 ( s )+ 2 H+ (aq)>Ca2+ (aq) + H2Carbon monoxide3(aq) ] which in bend reacts with Ca carbonate. There will be a point where the sum of carbonaceous acid produced will take down the sum of Ca carbonate.
With regard to titration, it should non be performed utilizing precipitates. Furthermore, aqueous solution of salt should be used in making titration with acids.
In titration experiments, the undermentioned points must be observed to raise the degree of truth of the consequences.
The solution in the volumetric flask should be exhaustively assorted.
The burette and pipette being used should be washed with the solutions being used.
The conelike flask should be exhaustively washed out with distilled H2O between titrations.
When an index is used in a titration, merely the minimal figure of beads is added each clip.
“A Pipette should merely be used if it is within plus or minus 1.0 % of the expected value.” [ 39 ] It should be carefully calibrated through hydrometric method.
To forestall carry over mistakes, the stuffs, such as pipettes should be “rinsed and dried between samples.” [ 40 ]
The consequences obtained in this probe suggest that the simple trial for the presence of C dioxide can non be modified to quantitatively measure the sum of C dioxide, despite its effectivity in determining its presence in a mixture. Furthermore, the precipitate formed in the reaction involved in the trial can non be used in titration with hydrochloric acid in order to cipher for the sum of C dioxide nowadays in the solution. The method which successfully measured the sum of C dioxide in this probe is the readying of C dioxide, whereby stoichiometry, was employed in the computation. In the concluding analysis, it is clear that the trial for C dioxide is a simple, yet effectual method of analyzing the presence of C dioxide. However, it does non supply the exact sum of the gas nowadays in the mixture. Furthermore, this probe fortifies an already established fact that titration is used specifically in the finding of the concentration of acids and bases in solutions [ 41 ] and non in the quantification of gases in mixtures.
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