In the experiment "Preparation and Standardization of a Sodium Hydroxide Solution", why was the burette rinsed with NaOH before filling it to "zero" for the titration?
Answer: The correct option is ALL OF THE ABOVE.
Explanation:
TITRATION is a type of volumetric analysis which is used for determining the concentration of solutions. In this process a specific volume of a solution is placed in a conical flask by means of a pipette and small quantities of a second solution is slowly added from a burette until the end point is reached. This is determined by a means of an indicator which shows a characteristic colour change.
During titration, the following precautions should be followed to avoid errors and maintain standardisation in the experiment.
--> Any air bubble in the burette and pipette must be removed during measurement
--> the burette tap should be tightened to avoid leakage.
--> Remove the funnel from the burette before taking any reading to avoid errors in reading the volume.
--> use the base solution such as Sodium Hydroxide Solution to rinse the burette after washing with soap and tap water:
• to remove any air bubble and fill it's tip
• to remove any residual liquid from the water and soap solution which may interfere with the results of the experiment.
• to check if the burette is in good condition.
Therefore all of the above options to the question are correct.
PLEASE HELP!!
Solutions Pre-Lab Questions:
In this lab, you will make fruit drinks with powdered drink mix. Complete the pre-lab questions to get the values you need for your drink solutions.
1. Calculate the molar mass of powered fruit drink mix, made from sucrose (C12H22O11).
2. Using stoichiometry, determine the mass of powdered drink mix needed to make a 1.0 M solution of 100 mL.
(Hint: Use molarity = to find the moles of drink mix, then convert moles to grams using a mole conversion.)
3. What mass of powdered drink mix is needed to make a 0.5 M solution of 100 mL?
Answer:
Explanation:
C₁₂H₂₂O₁₁
1 )
Molar mass = 12 x 12 + 22 x 1 + 11 x 16
= 144 + 22 + 176
= 342 g
2 )
100 mL of 1.0 M will contain 1.0 x0.100 = .1 mole of sucrose
0.1 mole of sucrose = 0.1 x 342 g = 34.2 g of sucrose.
So , mass of sucrose required is 34.2 g .
3 )
100 mL of .5 M sucrose = .100 x .5 mole of sucrose
= .05 mole of sucrose
.05 mole of sucrose = .05 x 342 g = 17.1 g of sucrose .
So , mass of sucrose required is 17.1 g .
Answer the following questions: (Questions about titration)
a. Why is it important to keep the NaOH solution covered at all times?
b. How will the molarity of NaOH solution be affected by its continued exposure to the atmosphere?
c. The pale pink color of the titration solution at the end point will fade to colorless after several minutes when exposed to the atmosphere. Account for this color change.
d. What volume (in mL) of 0.293 M Ba(OH)2 is required to neutralize 25.00 mL of 0.200M HNO3?
Answer:
Following are the solution to the given question:
Explanation:
For question a:
It is prevented that the atmospheric [tex]CO_2[/tex] through dissolving in the solution and make carbonic acid [tex](H_2CO_3)[/tex] which reacts with the [tex]NaOH:[/tex]
[tex]CO_2+ H_20\to H_2CO_3\\\\H_2CO_3 + NaOH \to NaHCO_3 +H_2O\\\\H_2CO_3 + 2 NaOH \to Na_2CO_3 + 2H_2O\\\\[/tex]
For question b:
For this, the [tex]NaOH[/tex] reacts with the dissolved [tex]CO_2[/tex] so, the molarity of the [tex]NaOH[/tex] will be decreased.
For question C:
In this, the Phenolphthalein is pink in the basic solution[tex](high \ pH)[/tex] and colorless throughout the acidic solution[tex](low\ pH)[/tex].
if the solution is exposed from the atmosphere, the [tex]CO_2[/tex] is from the air dissolving in the solution, and making the [tex]H_2CO_3[/tex] that gives the [tex]H^{+}\ ions[/tex]
[tex]\to[/tex] lower pH.
[tex]\to[/tex] colorless phenolphthalein
For question D:
[tex]Ba(OH)_2 + 2 HNO_3 \to Ba(NO_3)_2+ 2H_2O\\\\[/tex]
Calculating the moles of[tex]HNO_3 = volume \times \text{concentration of} HNO_3\\\\[/tex]
[tex]= \frac{25}{1000} \times 0.200\\\\= 0.005\ mol\\\\[/tex]
Calculating the moles of [tex]Ba(OH)_2= \frac{1}{2} \times\text{moles of}\ HNO_3\\\\[/tex]
[tex]=\frac{1}{2} \times 0.005\\\\= 0.0025 \ mol\\\\[/tex]
Calculating the volume of [tex]Ba(OH)_2=\frac{moles}{concentration\ of\ Ba(OH)_2}[/tex]
[tex]=\frac{0.0025}{0.0293}\\\\=0.08532\ L\\\\= 85.32 \ mL\\\\= 85.3\ mL[/tex]
A 1.19 g sample of an unknown halogen occupies 109 mL at 398 K and 1.41 atm. What is the identity of the halogen
Answer:
The halogen is Iodine.
Explanation:
Using the ideal gas equation, we find the number of moles of gas present, n.
PV = nRT where P = pressure of gas = 1.41 atm, V = volume of gas = 109 mL = 0.109 L, n = number of moles of gas, R = molar gas constant = 0.082 L-atm/mol-K and T = temperature of gas = 398 K
Since PV = nRT, making n subject of the formula, we have
n = PV/RT
substituting the values of the variables into the equation, we have
n = 1.41 atm × 0.109 L/(0.082 L-atm/mol-K × 398 K)
n = 0.15369 atm-L/32.636 L-atm/mol
n = 0.0047 mol
Since n = m/M where m = mass of gas = 1.19 g and M = relative molecular mass of gas
So, M = m/n
M = 1.19 g/0.0047 mol
M = 252.7 g
Since halogens are diatomic the relative atomic mass is M/2 = 252.7g/2 = 126.34 g
From tables, the only halogen with this atomic mass is Iodine.
So, the halogen is Iodine.
Suppose, in an experiment to determine the amount of sodium hypochlorite in bleach, you titrated a 23.92 mL sample of 0.0100 M K I O 3 with a solution of N a 2 S 2 O 3 of unknown concentration. The endpoint was observed to occur at 13.80 mL . How many moles of K I O 3 were titrated
Answer:
2.39x10⁻⁴ moles
Explanation:
As the problem asks us the number of moles of KIO₃ that were titrated, all that is required of us is to calculate how many moles of KIO₃ are there in 23.92 mL of a 0.0100 M solution (All moles in the samples are titrated).
We can do so by using the definition of molarity:
Molarity = moles / litersconverting 23.92 mL ⇒ 23.92 / 1000 = 0.02392 L
moles = 0.0100 M * 0.02392 Lmoles = 2.39x10⁻⁴ molesDescribe the electron configuration of an atom using principal energy level, sublevels, orbitals, and periodic table. Give one example others may not think about and why you made this selection.
Silicon is not allowed.
Explanation:
The electron density number as well as the sublevel letter are used to describe valence electrons in an atom. The third total energy and subbasement p, for example, is denoted by 3p. The electron configuration of oxygen, for example, is 1s^2 2s^2 2p^4, which means the first two electrons will couple up in the 1s orbital, while the following two protons will pair up in the 2s orbital.
The sample atom is Carbon with electron configuration; 1s² 2s² 2p².
The principal energy level of an electron refers to the shellp in which the electron is located relative to the atom's nucleus. In this case only 2 energy levels exist in a carbon atom; which are energy level 1 and 2
The sublevels exist within a principal energy and the electron configuration of an atom is described with consideration of energy sublevels. The sublevels in a carbon atom are;
s and p energy sublevels.The orbitals in this configuration are: 1s 2s 2px 2py 2pz in which case; each orbital can accommodate 2 electrons each.
Ultimately, the location of an element on the periodic table with respect to group and period are used to determine the valency and no. of energy levels in the atom of that Element.
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Wine goes bad soon after opening because the ethanol dissolved in it reacts with oxygen gas to form water and aqueous acetic acid , the main ingredient in vinegar. Calculate the moles of acetic acid produced by the reaction of of ethanol. Be sure your answer has a unit symbol, if necessary, and round it to significant digits.
Answer:
The answer is "It takes 1,70 mol of ethanol".
Explanation:
To make acetic acid, we must first write the balanced reaction that occurs of ethanol with oxygen
The response is balanced:
[tex]CH_3CH_2OH+O_2\to CH_3COOH+H_2O[/tex]
1 mol of ethanol creates 1 mol of According the equilibrium Ethanol moles, therefore, required 1.70 mol of water = 1.70 mol
State two conditions necessary for an esterification reaction to take place
Explanation:
Esterification occurs when a carboxylic acid reacts with an alcohol. This reaction can only occur in the presence of an acid catalyst and heat. It takes a lot of energy to remove the -OH from the carboxylic acid, so a catalyst and heat are needed to produce the necessary energy.
Answer:
The Esterification ProcessThe Esterification ProcessEsterification occurs when a carboxylic acid reacts with an alcohol. This reaction can only occur in the presence of an acid catalyst and heat. It takes a lot of energy to remove the -OH from the carboxylic acid, so a catalyst and heat are needed to produce the necessary energy.
The Esterification ProcessEsterification occurs when a carboxylic acid reacts with an alcohol. This reaction can only occur in the presence of an acid catalyst and heat. It takes a lot of energy to remove the -OH from the carboxylic acid, so a catalyst and heat are needed to produce the necessary energy.Once the -OH has been removed, the hydrogen on the alcohol can be removed and that oxygen can be connected to the carbon. Because the oxygen was already connected to a carbon, it is now connected to a carbon on both sides, and an ester is formed.
The Esterification ProcessEsterification occurs when a carboxylic acid reacts with an alcohol. This reaction can only occur in the presence of an acid catalyst and heat. It takes a lot of energy to remove the -OH from the carboxylic acid, so a catalyst and heat are needed to produce the necessary energy.Once the -OH has been removed, the hydrogen on the alcohol can be removed and that oxygen can be connected to the carbon. Because the oxygen was already connected to a carbon, it is now connected to a carbon on both sides, and an ester is formed.The methyl acetate that was formed is an ester. In this image, the green circle represents what was the carboxylic acid (in this case acetic acid), and the red circle represents what was the alcohol (in this case methanol):
This reaction lost an -OH from the carboxylic acid and a hydrogen from the alcohol. These two also combine to form water. So any esterification reaction will also form water as a side product.
In the reactionpyruvate lactatethat is catalyzed by the enzyme lactate dehydrogenase, the compound on which the enzyme works, pyruvate, is called the _______.
Answer:
Substrate
Explanation:
In biochemical sciences, a substrate is a substance that is acted upon by an enzyme to yield a product. Enzymes are known for catalyzing biochemical reactions. The substances that are usually worked with during this catalytic process are termed as SUBSTRATES.
Substrates, which are usually changed during the process, binds to the active site on the enzyme and form an enzyme-substrate complex.
According to this question, pyruvate is converted to lactate in a reaction that is catalyzed by the enzyme lactate dehydrogenase. This means that the compound on which the enzyme works, pyruvate, is called the SUBSTRATE.
Aluminum hydroxide, with heat, creates____
Answer:
Water and Aluminium oxide
Explanation:
Have a nice day.
Consider the balanced chemical equation below.
2 A ⟶ C + 4 D
How many moles of D would be produced if 6 moles of A were used?
Explanation:
[tex]here \: is \: your \: explanation : - \\ \\ given \: balanced \:equation \: = > \\ \\ 2 A=>C \: + \: 4D \\ \\ by \: this \: equation \: we \: get \: \\ \\ 2 \: moles \: of \: A \: produce \: 4 \: moles \: \\ \\ of \: D \\ \\ hence \: . \: 1 \: mole \: can \: produce \: = 4 \div 2 \\ \\ = > 2 \: moles \: \\ \\ so \: if \: 6 \: moles \: of \: A \: used \: then \: \\ \\ amount \: of \: D \: produced \: = (6 \times 2) \\ \\ = > 12 \: moles \: of \: D \\ \\ \mathcal\blue{ Hope \: it \: helps \: you \: (. ❛ ᴗ ❛.) }[/tex]
What is the difference between conjugate acid-base pair?
a. a H atom. c. a mole water
b. a H+ ion d. a OH– ion
Answer:
b. a H+ ion
Explanation:
The concept of conjugate acid-base pair is related to Bronsted-Lowry acid-base theory and according to this theory, acid is a proton acceptor.
In short,
conjugate base is formed when an acid donates a proton.
conjugate acid is formed when a base accepts a proton.
what the movement of the earth around the sun
Answer:
Yan po Ang sagot NASA pic
Explanation:
pa heart po plss
at pa vote
CORRECT ME IF IM WRONG
FOLLOW ME AND I FOLLOW BACK YOU☺️☺️☺️♥️♥️
Answer:
The movement of the earth around the sun in a fixed path or orbit is called Revolution. The axis of the earth which is an imaginary line, makes an angle of 66½° with its orbital plane. ... The earth takes about 24 hours to complete one rotation around its axis.
which of the following is the unit of surface tension?
Answer:
it should be N/m or newton per meter.
Part A of the lab involved adding 4 mL increments of distilled water to 5.00 mL of antimony trichloride solution. The antimony trichloride solution contains 0.10 M SbCl3 in 4.5 M HCl. Calculate the concentrations of SbCl3 and H /Cl- in the test tube after 12.0 mL of distilled water has been added. Assume dilution only.
Answer:
0.0238M SbCl3, 1.07M H+, 1.14M Cl-
Explanation:
The total volume of the solution is:
4mL + 5.00mL + 12.0mL = 21mL
As the volume of the SbCl3 is 5.00mL, the dilution factor is:
21mL / 5.00mL = 4.2 times
The concentration of SbCl3 is:
0.10M SbCl3 / 4.2 times = 0.0238M SbCl3
The concentration of H+ = [HCl]:
4.5M / 4.2 times = 1.07M H+
The initial concentration of Cl- is:
3 times SbCl3 + HCl = 0.10M*3 + 4.5M =
3 times SbCl3 because 1 mole of SbCl3 contains 3 moles of Cl-
4.8M Cl- / 4.2 times = 1.14M Cl-
A soluble unknown has contaminated your sample. It absorbs the same wavelength as your analyte, Allura Red dye. How will this affect your results, and what type of error is introduced
Answer:
The explanation as per the given query is presented in the following paragraph.
Explanation:
The Allura Reds Pigment or coloring increases the absorption by absorbing at around a very similar wavelength as that of the analysis.Therefore, the approximated analysis concentration or its intensity seemed substantially higher than that of the authentic one. Some positive mistake is going to exist.Thus the above is the correct explanation.
The measured absorbance will be higher, thereby creating systematic error.
Absorbance can be defined as the value or quantity of light absorbed by a given sample.The presence of impurity with a similar absorption wavelength will increase the absorbance. Moreover, systematic error is a type of error that is repeated along with different processes of measurement.In conclusion, the measured absorbance will be higher, thereby creating systematic error.
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A chemist combines 33 g of methane with 289 g of oxygen to from 189 g of carbon dioxide and 30 g of water. Determine if the results of the following word problem adheres to the Law of Conservation of Mass.
Answer:
The correct answer is - no not adhere to the law of mass conservation.
Explanation:
According to the law of mass conservation in an isolated system, the mass can not be created or destroyed and in a chemical or physical change, the mass of products should be always equal to the mass of reactants.
On the basis of the law the mass of the chemical reaction-
Mass of products = mass of reactants
33 g of methane + 289g of oxygen = 189g of carbon dioxide + 30g of water
322g ≠ 219 g
which means this reaction does not adhere to the law of conservation.
howtocalculatethevolumeofcarbondioxideproducedwhen400gofmarblewereats.t.p
Answer:
so 0.15 moles X 22.4 dm3/mole=3.36 dm3. Next we find the moles of hexane combusted, and then the moles of CO2. Finally, we find the volume of CO2 using the fact that at STP, 1 mole of gas = 22.4 dm3.
The energy needed to collapse the H-bonding of ice is _____.
it depends on the widths of the recesses, and if it is causing the shelf to fracture and collapse into the sea, then a massive iceberg could be called from the life she,f and the ice shelf are way more important because it holds it up
How many moles of carbon dioxide at Stp will fit in a 50 liter container?
Answer:
If the gas is at STP, THE 1 mole is 22.4 liters.
Explanation:
why do the Philippines have generally warm temperature throughout the year?a. it is near the sun b.it has many volcanoes c. it lies near the equator d. it has many islands.what is the correct answer?
Answer:
F. When everyone is together it gets hotter
Explanation:
Answer:
c. it lies near the equator
define a fluid very sort answer
Answer:
A fluid is a medium that has a defined mass and volume, but no fixed shape, at a constant temperature and pressure. This may include gases, liquids, plasmas, and to some extent plastic solids. A fluid can flow and deform, preventing it from carrying loads in a static equilibrium. A fluid is always compressible and internal frictional forces always occur due to the viscosity of the fluid.
Consider the arrangement of gases shown below. If the value between the gases is opened and the temperature is held constant, determine the following.
Answer:
I don't know what to say . just for points
What happens when Sulphur dioxide (so2) gas is passed through an acidified solution of hydrogen . sulfide (H₂S) gas :
Answer:
When SO
2
is passed through an acidified solution of H
2
S, sulphur is precipitated out according to the reaction.
2H
2
S+SO
2
→2H
2
O+3S
Which diagram correctly depicts the trend in electronegativity?
a.
b.
c.
d.
The electronegativity increases across the period and decreases down the group. Thus, option B is correct.
Electronegativity can be defined as the tendency of an atom to gain or attract an electron. The electronegativity has been dependent on the size of the atom, as well as the atomic number and valence electrons.
The atom with the requirement of a less number of atoms to complete its octet can easily gain the electron and thereby have high electronegativity. The atomic size also plays a role in the electronegativity of the atom.
The atom with a bigger size has the lesser force of attraction from the nucleus and thus has difficulty attracting the electron, however, the smaller size atom can easily attract the electron with the attraction force from the nucleus.
Thus, the elements with smaller sizes and a high number of valence electrons are more electronegative. In the periodic table, on moving from left to right the valence electrons increase, thus the electronegativity increases.
On moving down the group, the element size increase, thus the electronegativity decreases down the group.
The electronegativity increases across the period and decreases down the group. Thus, option B is correct.
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A sample of Br2(g) takes 12.0 min to effuse through a membrane. How long would it take the same number of moles of Ar(g) to effuse through the same membrane
Answer:
6 mins
Explanation:
The time taken for Ar to effuse can be obtained as follow:
Time for Br₂ (t₁) = 12 mins
Molar mass of Br₂ (M₁) = 2 × 80 = 160 g/mol
Molar mass of Ar (M₂) = 40 g/mol
Time for Ar (t₂) =?
t₂/t₁= √(M₂/M₁)
t₂ / 12 = √(40/160)
Cross multiply
t₂ = 12 × √(40/160)
t₂ = 12 × 0.5
t₂ = 6 mins
Therefore, it will take 6 mins for the same amount of Ar to effused out.
Calculate the mass of butane needed to produce 80.0g of carbon dioxide
Answer:
Multiply the number of moles of butane by its molar mass, 58.12g/mol, to produce the mass of butane. Mass of butane = 18.8g.
An unidentified gas is determined to be 24.0% carbon and 76% fluorine by mass. What is the empirical formula of this gas
Answer:
CF₂
Explanation:
Let's assume we have 100 g of the gas. If that were the case we'd have
24 g of C76 g of FNow we convert both masses into moles, using their respective molar mass:
24 g C ÷ 12 g/mol = 2 mol C76 g F ÷ 19 g/mol = 4 mol FWe can express those results as C₂F₄.
To determine the empirical formula we reduce those coefficients to the lowest possible integers, leaving us with CF₂.
The molar ratio of HPO42- to H2PO4- in a solution is 1.4. Calculate the pH of the solution. Phosphoric acid (H3PO4) is a triprotic acid with 3 pKa values: 2.14, 6.86, and 12.4.
Given is the ratio of conjugate base and conjugate acid of phosphoric acid. pH of a substance is the concentration of the hydrogen ions in its solution and higher this concentration lower is the value of pH.
pKa value is a measure of the strength of acid, it is the negative log of acid dissociation constant Ka.
Calculate the moment of inertia of a CH³⁵CL₃ molecule around a rotational axis that contains the C-H bond. The C-Cl bond length is 177pm and the HCCl angle is 107⁰f
Answer:
The correct answer is "[tex]4.991\times 10^{-45} \ kg.m^2[/tex]".
Explanation:
According to the question,
[tex]R_{C-Cl} = 177 \ pm[/tex]
or,
[tex]=1.77\times 10^{-10} \ m[/tex]
[tex]\alpha = 107^{\circ}[/tex]
[tex]m_{Cl}=34.97 \ m.u[/tex]
or,
[tex]=34.97\times 1.66\times 10^{-27}[/tex]
[tex]=5.807\times 10^{-26} \ kg[/tex]
The moment of inertia around the rotational axis will be:
⇒ [tex]I=3\times m_{Cl}\times (R_{C-Cl})^2 \ Sin^2 \alpha[/tex]
By putting the values, we get
[tex]=3\times 5.807\times 10^{-26}\times (1.77\times 10^{-10})^2 \ Sin^2 (107)[/tex]
[tex]=3\times 5.807\times 10^{-26}\times (1.77\times 10^{-10})^2\times 0.91452[/tex]
[tex]=4.991\times 10^{-45} \ kg.m^2[/tex]
