Answer:
Explanation:
Since the student fills up the buret with NaOH without rinsing it with small amount of NaOH , the water that is remaining stuck with the walls of the buret will dilute the solution of NaOH and it will result in lowering the morality of the solution . The molar concentration of the NaOH will no longer remain the same . It will lead to wrong calculation and hence wrong result.
The washing of burette in titration with NaOH solution results in the maintaining the concentration of the NaOH in the solution and allows the correct calculation of the molarity.
What is titration?The titration has been the reaction of the acid with the base resulted in the formation of salt and water and had the neutralization reaction.
The molarity of the base has been used in the analysis of the acid concentration on the neutralization reaction.
The skipping of the step of washing with NaOH resulted in the altering in the concentration of the NaOH with the stuck water on the walls of the burette, and thereby resulted in wrong calculation.
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Which compound would you expect to have the lowest boiling point?
a)CH3-CH2-CH2-CH2-CH2-CH3
b)CH3-CH2-OCH2-CH2-CH3
c)CH3-CH2-CH2-CH2-CH2-OH
d)CH3-CH2-OCH(CH3)2
e)CH3-OCH2-CH2-CH2-CH3
Answer:
d one is correct answer
Compounds are substances made by chemical bonding between elements and molecules. CH₃-CH₂-OCH(CH₃)₂ has the lowest boiling point. Thus, option D is correct.
What is the boiling point of a functional group?The boiling property and the functional group determine the property of the organic molecule. The boiling property of the molecules is defined by the intermolecular forces, the number of carbons (molecular mass), and branching.
The presence of functional groups like bonds (double and triple), carbonyl, halogens, and alcohol increases the boiling point of the substances. The given substances are:
CH₃-CH₂-CH₂-CH₂-CH₂-CH₃ - hexane (alkane)CH₃-CH₂-OCH₂-CH₂-CH₃ - ethoxyethane (ether)CH₃-CH₂-CH₂-CH₂-CH₂-OH - Pentan-1-ol (alcohol) CH₃-CH₂-OCH(CH₃)₂ - 2-ethoxypropane (ketone)CH₃-OCH₂-CH₂-CH₂-CH₃ - methyl propyl ether (ether)The order of boiling point is given as:
hexane (alkane)> ethoxyethane (ether)> methyl propyl ether (ether)> Pentan-1-ol (alcohol) > 2-ethoxypropane (ketone).
Therefore, option D. 2-ethoxypropane (ketone) has the least boiling point.
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Cis-3-tert-Butylcyclohexanol has the tert-butyl group in the equatorial position and the alcohol in the ________ position.
Answer:
Axial
Explanation:
In the most stable conformation of Cis-3-tert-Butylcyclohexanol, the tert-butyl group is at equatorial position and the alcohol group is in the axial position.
If the tert-butyl group is placed in equatorial position, repulsions are minimized. The bulkier the group, the greater the energy difference between the axial and equatorial conformers. Hence for a ring having a bulky substituent, such bulky substituent is better placed in the equatorial position.
The energy difference between the conformers of Cis-3-tert-Butylcyclohexanol is so high that the compound is almost "frozen" in a conformation where the tert-butyl groups are equatorial and the -OH groups are axial. This conformer is more stable by 24 KJ/mol.
Cis-3-tert-Butylcyclohexanol has the molecular formula of [tex](\rm C_{10}H_{20}O)[/tex]. The alcohol group in the compound is found at the axial position.
What are the groups and their positions?In the compound Cis-3-tert-Butylcyclohexanol alcohol is the functional group present at the axial position and tert-butyl group at the equatorial position of the compound.
Tert-butyl group at the equatorial position minimizes the repulsive forces and are bulky groups, the position of the bulkier groups at the equatorial positions are better as the energy differences will be large.
The difference in the energy of the conformers of the compound is high and the conformation of the compound remains as it is.
Therefore, tert-butyl groups are at equatorial and the alcohol groups are at axial.
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Which two chemical formulas represent molecules?
Answer:
There are three basic types of chemical formula, the empirical formula, the molecular formula, and the structural formula.
The equilibrium constant for the chemical equation N2(g)+3H2(g)↽−−⇀2NH3(g) is Kp=0.0133 at 181 ∘C. Calculate the value of Kc for the reaction at 181 ∘C.
Answer:
Kc is 18.478
Explanation:
Here we want to calculate Kc given Kp
The equation that links both is given as follows;
Kc = Kp/(RT)^Δn
where Kp = 0.0133
R is molar gas constant = 0.0821 L.atm/mol.k
T is temperature in kelvin = 181 + 273 = 454K
Δn is the change in number of moles between products and reactants = 2-4 = -2
Substituting these values, we have;
Kc = 0.0133/(0.0821 * 454)^-2
Kc = 18.478
4.47 x 10- 4 spook/ L is the value of Kc for the response N2( g) 3H2( g) 2NH3( g) at 181 °C.
Given
the chemical equation N2(g)+3H2(g)↽−−⇀2NH3(g) is Kp=0.0133 at 181 ∘C.
To Find
the value of Kc for the reaction at 181 ∘C.
Solution
In order to determine the value of Kc for the response N2( g) 3H2( g) 2NH3( g) at 181 °C, we can use the relationship between Kp and Kc.
This equation relates Kp with Kc
Kc = Kp( RT) n
where
Partial pressures are used to express Kp, the equilibrium constant.
In molar attention, Kc represents the equilibrium constant.
The gas constant, or R, is0.08206 L atm/ K spook.
The temperature in Kelvin is T.
The stoichiometric measure n is the difference between the aggregate of the gassy products' and gassy reactants' stoichiometric portions.
Then are the data
Δn = ( 2-( 1 3)) = -2
still, we get
If we substitute the values handed.
The formula for 0.0133 is Kc(0.08206 L/ atm/ Kmol *( 181 273) K)- 2.
When we simplify and find Kc, we gain
Kc equals4.47 x 10- 4 spook/L.
thus,4.47 x 10- 4 spook/ L is the value of Kc for the response N2( g) 3H2( g) 2NH3( g) at 181 °C.
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Cathode rays are deflected toward a negatively charged plate in an electric field.
True
False
Answer:
true. cathode rays are deflected
Please help, I really don’t understand this!!!
Analysing the Question:
We are given the balanced equation:
C₆H₁₂O₆ + 6O₂→ 6CO₂ + 6H₂O
from this equation, we can say that: for every 1 mole of Glucose, we need 6 moles of Oxygen
Moles of Glucose used in the reaction:
Molar mass of Glucose = 180 grams / mol
Given mass of Glucose = 1 gram
Mole of Glucose = Given mass / Molar mass
Moles of Glucose = 1 / 180 moles
Mass of Oxygen required:
We know that for every mole of Glucose, we need 6 moles of Oxygen
So, for 1/180 moles of Glucose, we need 6 / 180 = 1 / 30 moles of Oxygen
Mass of 1 / 30 moles of Oxygen:
Mass = Molar mass * number of moles
Mass of Oxygen = 32 * 1/30
Mass of Oxygen = 32 / 30
Mass of Oxygen = 1.06 grams
Enough of a monoprotic weak acid is dissolved in water to produce a 0.0129 M solution. The pH of the resulting solution is 2.65 . Calculate the Ka for the acid.
Answer:
Ka = 4.70x10⁻⁴M
Explanation:
The general dissociation of a weak acid, HX, is:
HX(aq) ⇄ H⁺(aq) + X⁻(aq)
And Ka is written as:
Ka = [H⁺] [X⁻] / [HX]
Where [] represents the molar concentration in equilibrium of each specie.
The equilibrium is reached when X of HX is dissociate in X H⁺ and X X⁻, that is:
[HX] = 0.0129M - X
[H⁺] = X
[X⁻] = X
As pH = -log [H⁺]:
10^-pH = [H⁺] = X = 2.239x10⁻³M
Solving:
[HX] = 0.0129M - 2.239x10⁻³M = 0.01066M
[H⁺] = 2.239x10⁻³M
[X⁻] = 2.239x10⁻³M
Ka = [H⁺] [X⁻] / [HX]
Ka = [2.239x10⁻³M] [2.239x10⁻³M] / [0.01066M]
Ka = 4.70x10⁻⁴M
The potential energy of a roller coaster is 50 joules. The kinetic energy of the same coaster is 50 joules. What is the mechanical energy of the coaster? O joules 50 joules 100 joules
Answer:
100 joules
Explanation:
The mechanical energy (M.E) of an object describes the objects ability to do work. The mechanical energy encompasses the object's energy due to its position (potential energy) and its energy due to motion (kinetic energy).
Therefore,
M.E = K.E + P.E
According to this question, potential energy (P.E) of the roller coaster is 50J and the kinetic energy (K.E) is also 50J. Hence, the mechanical energy (M.E) is
M.E = 50J + 50J
M.E = 100J
If the P.E and K.E of a roller coaster is 50 Joules respectively, the mechanical energy of the roller coaster is 100 Joules.
Given the following data:
Potential energy of roller coaster = 50 Joules.Kinetic energy of roller coaster = 50 Joules.To find the mechanical energy of the roller coaster:
The mechanical energy of a physical object or body is the total sum of the potential energy (P.E) and kinetic energy (K.E) possessed by an object.
Mathematically, mechanical energy is given by the formula;
Substituting the given parameters into the formula, we have;
[tex]M.E = 50 + 50[/tex]
Mechanical energy (M.E) = 100 Joules.
Therefore, the mechanical energy of the roller coaster is 100 Joules.
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12. In which layer of the sun do sunspots form?
A. Corona
B. Core
C. Convection zone
O D. Photosphere
Answer:
D
Explanation:
Photosphere is the layer where sunspots form.
Photosphere is the layer where sunspots form.
What is Photosphere?The Sun is made up of layers of material, like a baseball or rubber band ball. The photosphere is the lowest layer of the solar atmosphere. It is essentially the solar "surface" that we see when we look at the Sun in "white" (i.e. regular, or visible) light.
Like the Sun, our planet, Earth, is made up of layers, too. The thickest or most dense material on the Earth is in the very middle of our planet -- the core.
The thinnest is at the very top of our atmosphere - right next to outer space. The same is true of the Sun. But, the layers in the Sun and the Earth are much different.
Therefore, Photosphere is the layer where sunspots form.
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How many moles are found in 10.5 g of Pb?
Answer:
Number of moles = 0.05 mol
Explanation:
Given data:
Mass of Pb = 10.5 g
Number of moles of Pb = ?
Solution:
Formula:
Number of moles = mass/molar mass
Molar mass of Pb is 207.2 g/mol.
Now we will put the values in formula.
Number of moles = 10.5 g/207.2 g/mol
Number of moles = 0.05 mol
What might a peasized gland within the skull be?
salivary gland
pituitary gland
mammary gland
sebaceous gland
Answer:
Explanation:
pituitary gland
Answer:
B
Explanation:
The pituitary gland is a pea-sized structure that is attached to the undersurface of the brain by a thin stalk.
Select the word that is incorrect in the paragraph and replace it with a word which makes the statement correct:
Group 2 elements have two valence electrons in their outer shell and are considered metals. In order to form an ion, a Group 2 element will
gain two electrons and form a cation.
Ions can be made by single element or covalently bonded group of elements. The covalently bonded group of elements is called polyatomic ions or polyatomic atoms. In order to form an ion, a Group 2 element will loose two electrons and form a cation.
What is Ions?Any species that contain charge whether it is positive charge or negative charge is called ions. The example of polyatomic ions are sulfate, phosphate, nitrate etc.
Cation is the species that loose electron and attain positive charge while anion is a species which gain electron and attains negative charge so when anion and cation combine in fixed ration the the overall charge of the molecule is zero that is molecule is neutral, the charge over cation and anion is also called oxidation state. In order to form an ion, a Group 2 element will loose two electrons and form a cation.
Therefore, in order to form an ion, a Group 2 element will
loose two electrons and form a cation.
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These elements look like steps on the periodic table. They share properties of both metals and nonmetals. Computer chips contain elements from this family.
A) these elements are nonmetals
B) These elements are radioactive
C) these elements are metalloids
D) these elements are metals
Answer:
The answer would be C the metalloid in computer chips is silicone, it has luster like metal but is brittle like non metal.
Explanation:
These elements look like steps on the periodic table. They share properties of both metals and nonmetals. These elements are metalloids. Thus option C is correct.
What is periodic table?Periodic table is defined as an arrangement of all known elements in order of increasing atomic number and recurrent chemical attributes.
It is also defined as an ordered grouping of the 118 known chemical elements.
Metals are defined as a substance that has a glossy appearance when freshly manufactured, polished, or shattered and conducts electricity and heat reasonably effectively.
Non metals are defined as a natural materials that are physically fragile and do not generate heat or electricity.
Metalloids are defined as a type of chemical element with properties that are mostly intermediate between those of metals and nonmetals.
Thus, these elements look like steps on the periodic table. They share properties of both metals and nonmetals. These elements are metalloids. Thus option C is correct.
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How many distinct dichlorination products can result when isobutane is subjected to free radical chlorination?
a. 1
b. 2
c. 3
d. 4
e. 6
Answer:
c. 3
Explanation:
Dicholorination of tertiary alkane ( i.e. isobutane) is a halogenation reaction which makes it possible to replace the alkyl functional group with halogenated chlorine.
When Isobutane is subjected to free radicals chlorination, three distinct dichlorination can be formed.
The mechanism of the formation of these products can be seen in the image attached below.
What is the momentum of a 1kg ball moving at 5m/s?
Answer:
5Ns
momentum= mass *velocity
=1*5
=5Ns
Suppose that Biuret reagent turns purple when it is added to an unknown substance. What can you conclude about the substance?
Answer:
the unknown substance is a protein
Explanation:
The biuret test is one of the tests for proteins. It can be used to detect peptide linkages. The biuret test is carried out in an alkaline solution. A coordination complex is formed leading to the appearance of a violet color.
Summarily, the biuret method is a colorimetric technique used to test for proteins and peptides. It involves the formation of a purple (violet) complex of Copper salts in alkaline solution.
Hence when the biuret reagent is added to an unknown substance and it turns purple, the unknown substance is a protein
A group of students are studying the movement of thermal energy. The teacher asks the students to place the palms of their hands flat on their tabletops and describe what is happening. Which statement below best describes why the table feels cold?
Answer:
The table feels cold because it is at a lower temperature than the students' hands, and thermal energy is being pulled into the table.
Explanation:
The thermal conductivity of the table is low and so it feels cold.
What is Thermal Conductivity?Thermal conductivity is the measure of the ability of a material to conduct heat.
The rate at which heat is transported by conduction through a material's unit cross-section area when a temperature gradient exits perpendicular to the area is known as thermal conductivity.
Thermal energy is the energy contained within a system that accounts for the temperature of the system.
The human body cannot measure the temperature of any object but it can feel the difference in the temperature.
If one body is at 20 degrees Celsius, and an object is at 30 degrees Celsius, then the body will feel hot when the object is touched.
Similarly, when the students touched the table, the conductivity of the wood is very low, and it feels cold.
The thermal energy of the table is lower than the thermal energy of the body.
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The density of wind-packed snow is estimated to be 0.35 g/cm^3. A flat roof that is 35 by 43 feet has 28 inches of snow on it. How many pounds of snow are on the roof?
Answer:
There are 76728.2 pounds of snow on the roof
Explanation:
To determine how many pounds of snow are on the roof,
First we will determine the mass of the snow in grams.
From the question,
Density of snow = 0.35 g/cm³
From
Density = Mass / Volume
To determine the mass, we will first find the volume.
From the question, a flat roof that is 35 by 43 feet has 28 inches of snow on it, that is, the height of the snow on the roof is 28 inches.
Area of the roof = 35 ft × 43 ft = 1505 ft²
Volume of the snow = Area of the roof × Height of the snow
Height of the snow = 28 inches
12 inches = 1 foot
∴ 28 inches = 28/12 feet = 2.3333 ft
Hence,
Volume of the snow = 1505 ft² × 2.3333 ft = 3511.62 ft³
Volume of the snow = 3511.62 ft³
This is the volume of the snow in cubic feet
Now, we will convert cubic feet (ft³) to cubic centimeter (cm³)
1 ft = 30.48 cm
and 1 ft³ = 30.48³ cm³ = 28316.84659 cm³.
If 1 ft³ = 28316.84659 cm³
∴ 3511.62 ft³ will be 3511.62 × 28316.84659 cm³ = 99438004.83 cm³
Hence, Volume of snow = 99438004.83 cm³
Now, we can determine mass of snow in grams
From
Density = Mass / Volume
Mass = Density × Volume
Mass = 0.35 g/cm³ × 99438004.83 cm³
Mass = 34803301.69 g
Now, we will convert the mass from grams to pounds
1 pound = 453.592 grams
If 453.592 grams = 1 pound
Then, 34803301.69 g will be 34803301.69 / 453.592 pounds = 76728.2 pounds
Hence, there are 76728.2 pounds of snow on the roof.
what is the first step in the scientific inquiry process
Answer:
make an observation that describes a problem
Explanation:
Answer:
The first step in the Scientific Method is to make objective observations.
Explanation:
....-
Which type of reaction has the general formula of AB + CD → AD + CB?
synthesis
decomposition
oxidation
replacement
Answer:
The answer is D. Replacement
The given reaction has been the symbolization for replacement reaction. Thus, option D is correct.
The given general reaction has been:
[tex]\rm AB\;+\;CD\;\rightarrow\;AD\;+\;CB[/tex]
In the given reaction, there has presence of compound AB and CD. The reaction between the two results in the formulation of AD and CB. In the reaction, the B has been more attracted by C and forms bond with C by replacing D.
In the same way, A has been more attracted with D and forms bond with D replacing C.
The type of reaction in which the more reactive element replaces the less reactive element has been termed as replacement reaction. Thus, the given reaction has been the symbolization for replacement reaction. Thus, option D is correct.
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what is the hydronium ion concentration in a solution formed by combining 750mL of 0.10M NaOH with 250mL of 0.30 M HCl
Answer:
[tex][H^+]=1x10^{-7}M[/tex]
Explanation:
Hello.
In this case, since the reaction between sodium hydroxide and hydrochloric acid has a 1:1 mole ratio between them:
[tex]NaOH+HCl\rightarrow NaCl+H_2O[/tex]
In order to compute the hydronium H⁺ concentration in the mixed volumes of the given solutions we first compute the moles of each reactant:
[tex]n_{NaOH}=0.750L*0.10mol/L=0.075mol\\\\n_{HCl}=0.250L*0.30mol/L=0.075mol[/tex]
As seen, since those amounts are the same, we infer all the acid and base are consumed so the pH is 7 because a neutral salt is produced, and the corresponding H⁺ concentration is:
[tex][H^+]=10^{-pH}=10^{-7}=1x10^{-7}M[/tex]
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how many atoms are in 20.34 grams of aluminum (Al)
A) 6.02 x 10^23 atoms
B) 4.54 x 10^23 atoms
C) 4.54 atoms
D) 548.8 grams
Notice that the value 12.01 grams of natural carbon is the same as the atomic mass value (12.01 amu). It also tells us that 20.34 grams of aluminum contains exactly 6.022 x 1023 atoms of aluminum.
✅
So, the answer is A) 6.02 x 10^23 atoms
IamSugarBee
Answer:
Option A: 6.03 * 10^23 atoms
what is the point of doing an experiment. Help thank you
Answer:
to find out how somethings work
Explanation:
Answer:
Doing experiments is good because when you try these possibilities you can learn about something that you've tried or see why this experiment didn't really work. It also helps you understand that not everything you try will work. that's why we experiment.
Explanation:
Hope this helps:)
You make up a solution of a diprotic acid, H2A, having pKa values of 5.0 and 9.0. Identify the primary, secondary, and tertiary species when you set the pH equal to 8.0 by addition of KOH.
Answer:
Explanation:
A solution with a pH value of 7 is neutral i.e neither acidic nor alkaline. A solution with a pH less than 7 is said to be acidic, while one with a pH value more than 7 is alkaline. Acidity increases as the value decrease below 7, while alkalinity increases as the value increase about 7.
Given that H2A is a diprotic weak acid have pKa values of 5.0 ad 9.0, it will undergo dissociation in the solution as:
NOTE: These reactions are reversible reactions.
[tex]\mathbf{H_2A \to H^+ + HA^- \ \ \ pKa = 5.0}[/tex]
[tex]\mathbf{HA^- \to H^+ +A^{2-} \ \ \ pKa = 9.0}[/tex]
Thus;
The primary species is HA⁻
The secondary species is A²⁻
what is the oxidation number of cesium in Cs2Cr2O7
+1 for each Cs, -2 for each O, +6 for each Cr
Which statement best describes the octet rule?
A. When an atom becomes an ion, it gains or loses electrons so that its valence shell holds eight electrons.
B. When an atom becomes an ion, it gains or loses protons so that its nucleus holds eight protons.
C. When an atom becomes an ion, it gains or loses eight electrons.
D. When an atom becomes an ion, it gains or loses eight neutrons.
Neon effuses 1.26 times as fast an an unknown gas at a particular temperature. What is the molar mass of the unknown gas
Answer:
31.75 amu
Explanation:
Using Graham's equation of effusion as depicted below:
V1/V2 = √m2/√m1
Where; v1 = speed of neon gas
V2 = speed of unknown gas
m1 = molar mass of neon gas
m2 = molar mass of unknown gas
According to this question: v1 = 1.26x, m1 = 20amu, v2 = 1x, m2 = ?
Hence,
1.26x/1x = √m2/√20
1.26/1 = √m2/4.472
√m2 = 4.472 × 1.26
√m2 = 5.635
m2 = 5.635²
m2 = 31.75 amu
Therefore, the molar mass of the unknown gas is 31.75 amu.
Which of the following is an example of a chemical change that occurs in your home?
A) Water boiling on the stove
B) Composting your own fertilizer
C) Smashing a window with a baseball
D) Adding food coloring to icing for a cake
The table below gives the numbers of protons, electrons, and neutrons in four atoms.
Number of neutrons
Number of protons
19
Number of electrons
9
Atom
1
12
3
collo
18
10
9
9
9
10
4
19
Based on the table, which atom has a charge of -12
O 1
O 2
03
4
Answer:
THE ANSWER IS D UR WELCOME.
Explanation:
Literally struggling with this concept.(problem set included below)
