Answer:
C. mg and Ca
Explanation:
These chemical elements are collectively called as the Alkaline Earth Metals. Calcium and Magnesium are two of the six elements that fall into this category. The outer electronic structure of all these elements is similar due to which they all have similarity in their chemical and physical properties. They are all shiny, though fairly soft but still harder than alkali metals. Further, these are usually white or silvery coloured elements.They react with water to form hydrogen gas and metal hydroxide and with oxygen, they form oxides.
What is cellulose and what does it do?
Answer:
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β linked D-glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes.
Explanation:
Answer:
Hope this helped.
Explanation:
Cellulose is a molecule, consisting of hundreds – and sometimes even thousands – of carbon, hydrogen and oxygen atoms. Cellulose is the main substance in the walls of plant cells, helping plants to remain stiff and upright. Humans cannot digest cellulose, but it is important in the diet as fibre.
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
Assuming that a cheese sandwich consists of 2 slices of bread and 3 slices of cheese, determine the number of whole cheese sandwiches that can be prepared from 44 slices of bread and 63 slices of cheese.
Answer:
21 is the max but with the bread ypu could make 22 if you had 3 more cheese
Suppose a student needs to standardize a sodium thiosulfate, Na2S2O3,Na2S2O3, solution for a titration experiment. To do so, he or she will react it with a solution of iodine. The student adds a 1.00 mL1.00 mL aliquot of 0.0200 M KIO30.0200 M KIO3 solution to a flask, followed by 3 mL3 mL of distilled water, 0.2 g0.2 g of solid KI,KI, and 1 mL H2SO4.1 mL H2SO4. The student then titrates the solution with sodium thiosulfate solution in order to determine the exact concentration of Na2S2O3.Na2S2O3. The end point of the titration is reached after 0.90 mL0.90 mL of Na2S2O3Na2S2O3 is dispensed from a microburet. What is the concentration of the standard sodium thiosulfate solution?
Answer:
0.133
Explanation:
reaction between KIO3 and KI in acidic medium
IO3⁻ +5I⁻ +6h⁺ → 3I₂ + 3H₂O
I₂ reacts with thiosulphate
NaS₂O₃ → 2Na⁺ + S₂O₃²⁻
net reaction
IO⁻₃ + 6H⁺ + 6S₂O₃³⁻ → I⁻ + 3S₄O₆²⁻ + 3H₂O
mole of KIO₃
= molarity x volume
[tex]\frac{0.02mol}{L} *0.01L[/tex]
= 0.00002mol
a mole of KIO₃ has reaction with 6 mol of S₂O₃²⁻
= 2x6x10⁻⁵
= 0.00012 mol
volume = 0.90 ml
1 ml = 0.001L
0.90ML = 0.0009L
to get concentration,
molarity/volume
= 0.00012/0.0009
= 0.133m
The concentration of the standard sodium thiosulfate solution is ; 0.133
The net chemical reaction equation
IO₃⁻ + 6H⁺ + 6S₂O₃³⁻ ----> I⁻ + 3S₄O₆²⁻ + 3H₂O
First step : Determine the moles of KIO₃
number of moles = molarity * volume
= 0.02 mol / L * 0.01 L
= 0.00002 mol
From the net chemical reaction equation
one ( 1 ) mole of KIO₃ reacts with 6 moles of S₂O₃²⁻
∴ number of moles in the reaction = 6 * 0.00002 = 0.00012 mol.
Final step : Determine the concentration of sodium thiosulfate solution
Given Volume = 0.90 ml = 0.0009 L
∴ concentration of sodium thiosulfate solution
= 0.00012 / 0.0009 = 0.133
Hence we can conclude that The concentration of the standard sodium thiosulfate solution is ; 0.133
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Which of the following best describes the structure of a nucleic acid?
a
Carbon ring(s)
b
Globular or fibrous
c
Single or double helix
d
Hydrocarbon(s)
You have a carbonate buffer with pH 10.3 and a concentration of 2.0 M. What is the buffer capacity of 100 mL of the buffer against 3.0 M CsOH?
Answer:
Explanation:
pH = 10.3
[ H] = 10⁻¹⁰°³
= 5 x 10⁻¹¹ M
concentration of CsOH C = 3 M
pKa of carbonate = 6.35
Ka = 10⁻⁶°³⁵ = 4.46 x 10⁻⁷
Buffer capacity = 2.303 x C x Ka x [ H⁺] / ( Ka + [ H⁺]² )²
= 2.303 x 3 x 4.46 x 10⁻⁷ x 5 x 10⁻¹¹ / ( 4.46 x 10⁻⁷ + 25 x 10⁻²² )²
= 154 x 10⁻¹⁸ / 19.9 x 10⁻¹⁴
= 7.74 x 10⁻⁴ .
Find ΔHrxn for the following reaction:
2PbS(s)+3O2(g)→2PbO(s)+2SO2(g)
Answer:
ΔH°rxn = -827.5 kJ
Explanation:
Let's consider the following balanced equation.
2 PbS(s) + 3 O₂(g) → 2 PbO(s) + 2 SO₂(g)
We can calculate the standard enthalpy of reaction (ΔH°rxn) from the standard enthalpies of formation (ΔH°f) using the following expression.
ΔH°rxn = [2 mol × ΔH°f(PbO(s)) + 2 mol × ΔH°f(SO₂(g) )] - [2 mol × ΔH°f(PbS(s)) + 3 mol × ΔH°f(O₂(g) )]
ΔH°rxn = [2 mol × ΔH°f(PbO(s)) + 2 mol × ΔH°f(SO₂(g) )] - [2 mol × ΔH°f(PbS(s)) + 3 mol × ΔH°f(O₂(g) )]
ΔH°rxn = [2 mol × (-217.32 kJ/mol) + 2 mol × (-296.83)] - [2 mol × (-100.4) + 3 mol × 0 kJ/mol]
ΔH°rxn = -827.5 kJ
The standard enthalpy of the reaction is -827.5 kJ/mol
The standard enthalpy of reaction [tex]\mathbf{\Delta H^0_{rxn}}[/tex] is the enthalpy change that happens in a system whenever one mole of the matter is converted through a chemical process under normal conditions.
The given reaction can be expressed as:
2PbS(s) + 3O₂(g) → 2PbO(s) + 2SO₂(g)
The standard enthalpy can be represented by the equation:
[tex]\mathbf{\Delta H^0_{rxn} = \sum \Delta _f ^0(products) - \sum \Delta _f^0(reactants)}[/tex]
At standard conditions, the standard enthalpies of formation of the given species are:
ΔH°f(PbO(s)) = 219 kJ/molΔH°f(SO₂(g)) = -296.83 kJ/molΔH°f(PbS(s)) = 100.4 kJ/molΔH°f(O₂(g)) = 0 kJ/mol
∴
[tex]\mathbf{ \Delta H^0_{rxn} = \Big[2 mol \times \Delta H^0_f(PbO(s)) + 2 mol \times \Delta H^0_ f(SO_2(g) )\Big] - \Big[2 mol \times \Delta H^0_f (PbS(s))} + \mathbf{ 3 mol \times \Delta H^0_f(O_2(g) )\Big] }}[/tex]
[tex]\mathbf{\Delta H^0rxn = [2 mol \times (-217.32 kJ/mol) + 2 mol \times (-296.83)] - [2 mol \times (-100.4)} \\ \mathbf{+ 3 mol \times 0 kJ/mol]}}[/tex]
[tex]\mathbf{\Delta H^0rxn = -827.5 \ kJ/mol}}[/tex]
Therefore, we can conclude that the standard enthalpy of the reaction is -827.5 kJ/mol
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How many moles of H2 are needed to produce 24 moles of NH3?
Answer:
36 mol of H2
Explanation:
The balanced equation of the reaction is given as;
3H2 + N2 --> 2NH3
From the reaction;
It takes 3 mol of H2 reacting with 1 mol of N2 to form 2 mol of NH3
3 mol of H2 = 2 mol of NH3
x mol of H2 = 24 mol of NH3
x = (24 * 3) / 2 = 36 mol of H2
How many lbs are in 5 kilograms ?
Answer:
11.023 pounds
Explanation:
Which of the following reactions would you expect to produce the most energy?
A. Nuclear fusion of two hydrogen isotopes.
B. Combustion of hydrogen gas.
C. Combination of a strong acid and a strong base.
D. Burning a large hydrocarbon, such as oil.
Answer:
A
Explanation:
Nuclear fusion is a much more powerful reaction than any of the others.
Nuclear fusion of two hydrogen isotopes would expect to produce the most energy. Therefore, option (A) is correct.
What is nuclear fusion?Nuclear fusion can be defined as when two or more nuclei fuse together to form a single heavier nucleus. In this reaction, the matter is generally not conserved due to some of the mass of the nuclei being converted to energy.
For nuclear fusion, the nuclei must be brought closer to the reaction occurring. Each star in the universe, including sun, is shining due to nuclear fusion reactions. They produce large amounts of energy in this process.
In the Sun's core, hydrogen nuclei are get transformed into helium nuclei which are known as nuclear fusion. It takes place when four hydrogen nuclei fuse into each helium nucleus. During the Nuclear fusion process, some of the mass of hydrogen nuclei is transformed into energy.
Therefore, nuclear fusion is where hydrogen atoms combined to form helium to produce the most energy.
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I NEED HELP ASAP
Types of Cells
1) I have a cell membrane?
PROKARYOTE
EUKARYOTE *******
BOTH
2)I have a nucleus *
PROKARYOTE*****
EUKARYOTE
BOTH
3)I am a bacteria *
PROKARYOTE
EUKARYOTE
BOTH
1) Both cells have a cell membrane.
2) A nucleus is present in only Eukaryote cells.
3) I'm pretty sure Prokaryote cells are bacteria.
Hope this helps!! :)
The # of electrons in S2- -34 is
Answer:
The answer is 16
Explanation:
What color is the acetic acid plus methyl orange solution and what does this tell you about where the equilibrium is
Answer:
Red
Explanation:
Acetic acid is an acidic medium. Recall that indicators are organic substances whose color changes in response to change in the pH of the solution. often times, the protonated and deprotonated forms of an indicator have different colors.
However, an equilibrium is set up when an indicator is in acid/ basic medium. Methyl orange is red in acid medium and yellow in basic medium.
Hence while in acetic acid, the equilibrium lies towards the protonated form of acetic acid, hence the solution appears red.
Help, 8th grade Science
What is the mass number of an element?
A. Mass number is the number of protons in the nucleus.
B. Mass number is the mass of the protons in the nucleus.
C. Mass number is the mass of the most abundant isotope.
D. Mass number is the atomic mass of a particular isotope.
The mass number of an element is the sum of the protons and neutrons present in the nucleus of the atoms of the element.
What is mass number?The mass number of an element is the number obtained when the number of protons and neutrons in the nucleus of an atom of the element are summed together.
The sum of protons and neutrons in the nucleus of an atom is collectively known as the nucleon. Thus, the mass number of an atom can also be referred to as the nucleon of the atom.
This can be mathematically expressed as:
Mass number = number of protons + number of neutrons.
Atoms generally contain protons, neutrons, and electrons. The protons are positively charged and are located in the nucleus, the neutrons are also located in the neucleus but have no charges. The electrons, on the other hand, are located outside the nucleus in regions referred to as orbitals.
The sum of the protons and neutrons determine the mass of an atom because the contribution of electrons to the mass of atoms is negligible.
Thus, the mass number of an element is the sum of proton and neutron numbers present in the nucleus of the atoms of the element.
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Having the same number of valence electrons means having similar chemical properties.
True or False
Answer:
True
Explanation:
Because atoms with the same number of valence electrons react in similar ways with other elements.
A certain chemical reaction releases of heat for each gram of reactant consumed. How can you calculate the heat produced by the consumption of of reactant? Set the math up. But don't do any of it. Just leave your answer as a math expression. Also, be sure your answer includes all the correct unit symbols.
Complete Question
The complete question is shown in the first uploaded image
Answer:
So the math expression is
[tex]heat = \frac{ 35. 7 KJ * 1900 \ gram }{ 1 \ gram }[/tex]
Explanation:
From the question we are told that
The heat released for 1 gram of reactant consumed is [tex]H = 37.5 \ KJ/g [/tex]
The mass of reactant considered is [tex]m = 1.9 \ kg = 1900 \ g[/tex]
So if
[tex]37.5 \ KJ [/tex] is produced for 1 gram
Then
x kJ is produced for 1900 g
=> [tex]x = \frac{ 35. 7 KJ * 1900 \ gram }{ 1 \ gram }[/tex]
So the heat released is
[tex]heat = \frac{ 35. 7 KJ * 1900 \ gram }{ 1 \ gram }[/tex]
Which property of a substance can be determined using a pH indicator?
A. acldity
B. bolling polint
C. density
D. electrical conductivity
E. thermal conductivity
Answer:
the correct answer would be A. acidity
Answer:
The answer is A.) Acidity
Rupert had three substances. A brown substance was a liquid at room
temperature. He hit each of the other two with a hammer. A blue crystal
cracked but did not break. A silver substance flattened but did not crack.
Which two statements could be true?
A. The brown substance is ionic
B. The silver substance is ionic
C. The brown substance is molecular
D. The blue substance is ionic
Answer:
its C and D
C. The brown substance is molecular
D. The blue substance is ionic
Explanation:
did the test !
Two correct statements are B) The silver substance is ionic
C) The brown substance is molecular.
What kind of substance is silver?Silver is a chemical element with the symbol Ag and atomic wide variety 47. categorized as transition steel, Silver is stable at room temperature.
Which substance is molecular?It is a molecular substance, that's a substance with or more atoms, the smallest gadgets of remember joined together via a covalent bond. A covalent bond is a hyperlink created via the sharing of electrons that holds these atoms collectively.
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Which pair of elements will form a covalent bond?
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.
Which of the following statements is true during a solar eclipse?
The moon's light is blocked by the Earth.
The Sun's light is blocked by the Earth.
The Sun's light is blocked from another planet.
The Sun's light is blocked by the Moon.
Answer:
The sun's light is blocked by the moon.
Explanation:
During the eclipse, the moon rotates right in front of the sun, that's why the eclipse is so rare and only happens every four(?) years/
The escape velocity from Earth’s surface is 1.12*10^4 meters per second. At this speed, how many kilometers would a rocket travel in 3 minutes
Answer:
2016 Km.
Explanation:
The following data were obtained from the question:
Speed (S) = 1.12×10⁴ m/s
Time (t) = 3 mins
Distance (d) =.?
Next, we shall convert 3 mins to seconds. This can be obtained as follow:
1 min = 60 s
Therefore,
3 mins = 3 min × 60 s / 1 min
3 mins = 180 s
Next, we shall determine the distance travelled by the rocket. This is illustrated below:
Speed (S) = 1.12×10⁴ m/s
Time (t) = 180 s
Distance (d) =.?
Speed (S) = distance (d) /time (t)
S = d/t
1.12×10⁴ = d/ 180
Cross multiply
d = 1.12×10⁴ × 180
d = 2016000 m
Finally, we shall convert 2016000 m to Km. This can be obtained as shown below:
1000 m = 1 Km
Therefore,
2016000 m = 2016000 m × 1 Km / 1000 m
2016000 m = 2016 Km
Therefore, the rocket will travel 2016 Km in 3 mins
How many liters of H2(g) at STP are produced per gram of Al(s) consumed in the following reaction? 2Al(s)+6HCl(aq)→2AlCl3(aq)+3H2(g)
Answer:
1.24 L of H₂ at STP .
Explanation:
2Al(s) +6HCl(aq) → 2AlCl₃(aq) + 3H₂(g)
2 moles 3 x 22.4 L
2 x 27 g of Al reacts to give 3 x 22.4 L of H₂ at STP .
1 g of Al will react to give 3 x 22.4 / ( 2 x 27 ) L of H₂ at STP .
= 1.24 L of H₂ at STP .
The volume of hydrogen produced by 1 grams of Al has been 1.24 L.
The balanced chemical reaction has been given as:
[tex]\rm 2\;Al\;+\;6\;HCl\;\rightarrow\;2\;AlCl_3\;+\;3\;H_2[/tex]
From the equation, 2 moles of Aluminum gives 3 moles of Hydrogen
The mass of the compound from moles can be given as:
Mass = moles × molecular mass
Mass of 2 moles Al = 2 × 27 g
Mass of 2 moles Al = 54 g
Mass of 3 moles hydrogen = 3 × 2 g
Mass of 3 moles hydrogen = 6 g
From the equation,
54 g aluminum gives = 6 grams hydrogen
[tex]\rm 1\;gram\;aluminum\;=\;\dfrac{6}{54}\;\times\;1[/tex]
1 gram Aluminum = 0.11 grams hydrogen
The mass of hydrogen produced by 1 gram Al has been 0.11g. The moles equivalent to 0.11g hydrogen has been given as:
Mass = moles × molecular mass
0.11 g = moles × 2 g/mol
Mole of hydrogen = 0.055 mol
The moles of hydrogen produced by 1 gram of Al has been 0.055 mol.
According to the ideal gas equation, any gas at STP has 1 mole equivalent to 22.4 L. So,
1 mol = 22.4 L
0.055 mol = 0.055 × 22.4 L
0.055 mol = 1.244 L.
The volume of hydrogen produced by 1 grams of Al has been 1.24 L.
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Which is the best molecule to build collegen, muscle repair, and tendon repair?
a
carohydrates
b
lipids
c
nucleic acids
d
Proteins
Answer:
d
Explanation:
collagen is made of proteins
characteristic line spectra only appear in the visible region of light. true or false
Answer:
The answer is true
Explanation:
bc I took this on edgeunity
What is an extremophile? What domain is known for these organisms?
Extremophiles are bacteria, archaea, as well as eukarya across all three domains of life. Cells make up every organisms.
What is Extremophiles?Extremophiles contain bacteria, archaea, as well as eukarya from all three domains of life.
What is organisms ?Any organic, biological system which works as a separate entity was referred to as an organism.
Extremophiles are organisms that can survive in harsh settings, such as those with high temperatures, radiation, salt, or pH levels. In the planet's evolutionary development, several creatures have been ecologically dominating.
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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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Carbonic acid, H2CO3, has two acidic hydrogens. A solution containing an unknown concentration of carbonic acid is titrated with potassium hydroxide. It requires 22.9 mL of 1.430 M KOH solution to titrate both acidic protons in 54.2 mL of the carbonic acid solution.
Required:
a. Write a balanced net ionic equation for the neutralization reaction. Include physical states.
b. Calculate the molarity of the carbonic acid solution.
Answer:
a. H₂CO₃(aq) + KOH(aq) ⇄ K₂CO₃(aq) + H₂O(l)
b. 0.603 M
Explanation:
Step 1: Write the neutralization reaction
H₂CO₃(aq) + KOH(aq) ⇄ K₂CO₃(aq) + H₂O(l)
Step 2: Calculate the reacting moles of KOH
22.9 mL of 1.430 M KOH react.
0.0229 L × (1.430 mol/L) = 0.0327 mol
Step 3: Calculate the reacting moles of H₂CO₃
The molar ratio of H₂CO₃ to KOH is 1:1. The reacting moles of H₂CO₃ are 1/1 × 0.0327 mol = 0.0327 mol.
Step 4: Calculate the molarity of H₂CO₃
0.0327 moles of H₂CO₃ are in a volume of 54.2 mL. The molarity of H₂CO₃ is:
M = 0.0327 mol/0.0542 L = 0.603 M
It is critical to watch or _________________ what is happening with every step of your experiment
It is critical to watch or observe what is happening with every step of your experiment