Answer:
1) The percentage of oxygen in dry air is _______
C. 21
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
B. CARBON DIOXIDE
Hope it helps
have a nice day
Answer: The percentage of oxygen in dry air is . 21
Explanation: Ammonia gases was present in large amounts in the easth7s earliest atmosphere
Hope it will help you
which among the following pairs are not isotopes?
Which of the following pairs lists a substance that can neutralize Ca(OH)2 and the salt that would be produced from the reaction?
HCl and CaCl2
HClO and CaHClO
H2O and Ca(OH)3
H3PO4 and Ca(PO3)2
Answer:
Which of the following pairs lists a substance that can neutralize Ca(OH)2 and the salt that would be produced from the reaction?
HCl and CaCl2
HClO and CaHClO
H2O and Ca(OH)3
H3PO4 and Ca(PO3)2
Explanation:
The given substance is Ca(OH)2 which is a base.
To neutralise a base an acid is required.
Among the given options,
HCl and H3PO4 are the acids.
The salts foremd when calcium hydroxide reacts with the respective acids are CaCl2 and Ca3(PO4)2.
But among the given options, only the forst option that is
HCl and CaCl2 shows the correct formulas.
Hence, the answer is first option.
Answer:
HCl and CaCl2
Explanation:
Which statement about biogeochemical cycles is true?
O A. Plants are a part of the nitrogen and carbon cycles, but not the
water cycle.
O B. Plants are a part of the nitrogen, carbon, and water cycles.
O c. Plants are a part of the water and carbon cycles, but not the
nitrogen cycle.
D. Plants are a part
carbon cycle.
the water and nitrogen cycles, but not the
Answer: The answer is D:
Answer:
The answer is Option D
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C. Yes, if each sample contains 6.02 x 10²³ atoms.
CH4 (g) + O2 (g) → CO2 (g) + H2O (g) to. If 28.6 g of CH4 is reacted with 57.6 g of O2, calculate the number of grams of CO2 produced. b. If you actually get 32.1 g of CO2, calculate the percent yield. c. Calculate the number of moles of excess reagent remaining at the end of the reaction.
Answer:
See explanation
Explanation:
First we must obtain the limiting reactant. The equation of the reaction is;
CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g)
Number of moles of CH4= 28.6 g/16g/mol = 1.8 moles
Since the reaction is 1:1, 1.8 moles of CO2 was produced
Number of moles of O2 = 57.6 g/32 g/mol = 1.8 moles
2 moles of O2 produced 1 mole of CO2
1.8 moles of O2 produced 1.8 × 1/2 = 0.9 moles of CO2
Hence O2 is the limiting reactant
Mass of CO2 produced = 0.9 moles × 44 g/mol = 39.6 g
%yield = 32.1g/39.6 g × 100
%yield = 81.1%
According to the reaction equation;
2moles of O2 reacts with 1 mole of CH4
1.8 moles of O2 reacts with 1.8 × 1/2 =0.9 moles of CH4
Number of moles of CH4 left = 1.8 moles - 0.9 moles
Number of moles of CH4 left = 0.9 moles
what is the formulas for Calcium Chloride,Aluminium Sulphate and Sodium hydroxide. *
Answer:
Explanation:
Why is there a star * behind the question.
CaCl2
Al2(SO4)3
NaOH
I need the answer to this asap!! please explain
Answer:
See explanation
Explanation:
Calcium carbide reacts with water to yield acetylene gas and calcium hydroxide as follows;
CaC2(s)+2H2O(g)⇋Ca(OH)2(s)+C2H2(g)
This now shows us that the equation as written in the question is wrong. Since the equation for the reaction of calcium carbide and water as shown in the question is wrong, the equation can not be balanced.
Among the given solutions of potassium permanganate (KMnO4), which one has the highest concentration of water in it?
Answer: Solution D has the highest concentration of all.
Explanation:
The formula used to calculate molarity:
[tex]\text{Molarity of solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (mL)}}[/tex] .....(1)
For A:Molarity of permanganate solution = 0.1 M
Volume of solution = [tex]100 cm^3=100mL[/tex] (Conversion factor: [tex]1mL=1cm^3[/tex])
Putting values in equation 1, we get:
[tex]0.1=\frac{\text{Moles of permanganate solution}\times 1000}{100}\\\\\text{Moles of permanganate solution}=\frac{100\times 0.1}{1000}=0.01mol[/tex]
For B:Molarity of permanganate solution = 0.01 M
Volume of solution = [tex]100 cm^3=100mL[/tex]
Putting values in equation 1, we get:
[tex]0.01=\frac{\text{Moles of permanganate solution}\times 1000}{100}\\\\\text{Moles of permanganate solution}=\frac{100\times 0.01}{1000}=0.001mol[/tex]
For C:Molarity of permanganate solution = 2 M
Volume of solution = [tex]100 cm^3=100mL[/tex]
Putting values in equation 1, we get:
[tex]2=\frac{\text{Moles of permanganate solution}\times 1000}{100}\\\\\text{Moles of permanganate solution}=\frac{100\times 2}{1000}=0.2mol[/tex]
For D:Molarity of permanganate solution = 2.5 M
Volume of solution = [tex]100 cm^3=100mL[/tex]
Putting values in equation 1, we get:
[tex]2.5=\frac{\text{Moles of permanganate solution}\times 1000}{100}\\\\\text{Moles of permanganate solution}=\frac{100\times 2.5}{1000}=0.25mol[/tex]
The solution having the highest number of moles will have the highest concentration for the same volume.
Thus, solution D has the highest concentration of all.
A mechanical wave starts when matter is disturbed by a source
of_______ I NEED ANSWER ASAP
Answer:
i believe energy is your answer here
8. Acetylene is the common name for (a) ethene (b) ethyne (c) propene (d) propyne
Answer:
ethene
Explanation:
The chemical compound acetylene (systematic name: ethyne) has the formula C2H2. It's a hydrocarbon and the most basic alkyne. Because its two carbon atoms are linked together in a triple bond, acetylene is unsaturated as an alkyne.And the ending of acetylene has ene which indicates that it's an alkene .And the ending of acetylene has ene which indicates that it's an alkene.
Answer: i think it is Ethyne
Explanation: because another name for Acetylene is Ethyne which is commonly known
Suppose that you chose sodium carbonate to precipitate the chromium ions from a solution of chromium (III) chloride. Write and balance the equation of this double-displacement reaction.
If the solution has a volume of 520 mL and the concentration of chromium (III) chloride is 0.224 M, how many grams of sodium carbonate should you add to the solution to precipitate out all the chromium ions?
Answer:
18.5g Na2CO3
Explanation:
Chromium (III) chloride, CrCl3, reacts with Na2CO3 as follows:
2CrCl3 + 3Na2CO3 → Cr2(CO3)3(s) + 6NaCl
Where 2 moles of CrCl3 react with 3 moles of Na2CO3 to produce 1 mole of Cr2(CO3)3 -The precipitate-
To solve this question we need to find the moles of CrCl3 added. With the chemical equation we can find the moles of Na2CO3 and its mass as follows:
Moles CrCl3:
520mL = 0.520L * (0.224mol/L) = 0.116 moles CrCl3
Moles Na2CO3:
0.116 moles CrCl3 * (3 mol Na2CO3 / 2mol CrCl3) = 0.175 moles Na2CO3
Mass Na2CO3 -Molar mass: 105.99g/mol-
0.175 moles Na2CO3 * (105.99g/mol) = 18.5g Na2CO3
Crystals of sodium chloride were prepared by the following method.
1 25.0 cm3
of dilute hydrochloric acid was accurately measured into a conical flask.
2 Aqueous sodium hydroxide was added until the solution was neutral. The volume of
sodium hydroxide added was measured.
3 The solution was evaporated and the crystals washed with approximately 15 cm3
of water.
Which row shows the pieces of apparatus used to measure the 25.0 cm3
of hydrochloric acid, the
volume of aqueous sodium hydroxide and the 15 cm3
of water?
Answer: the answer is C
IF U MIGHT NEED AN EXPLANATION FEEL FREE TO COMMENT
The laboratory equipment like the burette, pipette, and measuring cylinders are used in process of titration process. The solution of NaOH is added by the burette. Thus, option C is correct.
What is titration?Titration has been the analytical technique that uses the known and measured quantity of the solution to estimate the volume of another solution with an unknown volume and known molar concentration.
The laboratory equipment like burette, pipette, and measuring cylinders are used in measuring the volume in the titration process. The burette is filled with sodium hydroxide to measure its quantity.
The pipette is used to transfer the volume of the solution that is known (hydrochloric acid) and the measuring cylinder is used to measure the liquid (water) that is used in chemistry experiments.
Therefore, option C. pipette, burette, and measuring cylinder are the apparatus used in the titration process.
Learn more about titration, here:
https://brainly.com/question/10024565
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Si un carabinero está controlando velocidad en la carretera y pistolea mi vehículo, está midiendo mi rapidez media
Answer:
Si.
Explicación:
Si un oficial de policía está controlando la velocidad en la carretera y dispara al vehículo con una pistola de radar. El policía mide la velocidad media del coche con esta pistola de radar. Una pistola de radar es un dispositivo que se utiliza para medir la velocidad de los objetos en movimiento que fue inventado por Bryce K. Brown en el año de 1954. La pistola de radar se utiliza con fines policiales para calcular la velocidad de los vehículos en movimiento.
draw the atomic model of sulphur with the details and electronic configuration
here's your answer hope this will help
3. If there were multiple products comment on finding the mixture melting point of the products. Does your sample appear to be a mixture or pure
Answer:
If there were multiple products, we can take each product and mixed with a sample of a pure compound that we suspect might be the same as the product. Then, we taking the melting point of this mixture that contains one of our product and pure sample. Then, we can observe the change in melting point, if there is no change in melting point or the melting stays in the same range of the pure compound. Then, the that product along with the pure sample are actually the same compound, not a mixture of two compounds. However, if the melting point for our pure sample compound changed or didn't stay in the same range after the mixing with on of our products. then we can conclude that this product and the pure sample are completely different compound, and indeed they are a mixture.
Place the steps of the action potential in order.
- a brief reversal of membrane potential that travels along the axon
- mechanism that restores the resting membrane voltage and intracellular ionic concentrations
- reversal of the resting potential due to an influx of sodium ions
- period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability
Answer:
-Reversal of the resting potential due to influx of sodium ions
-Mechanism that restores the resting membrane voltage and intracellular ionic concentrations
-Period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability
-A brief reversal of membrane potential that travels along the axon
Explanation:
An action potential is a situation where the membrane potential is briefly reversed from -70mV to +30 mV
There are three steps of the moving action potential, including;
1) The depolarization step, where the membrane resting potential is reversed by the rush of sodium ions into a neuron
2) The repolarization, due to the closing of the voltage-gated sodium channels and the opening of the potassium channels, which is a mechanism that restores the membrane's resting voltage and the ionic concentration in the cell
3) Hyperpolarization, where due to some open potassium channels, there is an increased potassium permeability, and excessive efflux of potassium ions take place, which results in a dip in the membrane potential
4) The above three phases describe the phase of the action potential which is the brief reversal of membrane potential that travels along the axon
heyy guys, so basically i need help with stoichiometric calculation I will give you 100 points just to answer all of these answers accurately with working out (ps ill mark you brainliest x), thanks. PLEASE HELPPP. I'm desperate x
3. What masses of ethanol and ethanoic acid would need to be reacted together to give 1 g of ethyl ethanoate?
C^2H^5OH + CH^3CO^2 H → CH^3CO^2C^2H^5 + H^2O
4. What mass of iron(III) oxide would need to be reduced to produce 100 tonnes of iron in a blast furnace?
Fe^2^O^3 + CO → Fe + CO^2
5. What mass of silver nitrate as a solution in water would need to be added to 5 g of sodium chloride to
ensure complete precipitation of the chloride?
AgNO^3(aq) + NaCl (aq) → AgCl (s) + NaNO^3(aq)
6. Copper(II) oxide reacts with sulphuric acid to produce copper(II) sulphate. If this is allowed to crystallise the formula of the crystals is CuSO 4 .5H 2 O. What mass of copper oxide would be needed to produce 100 g of crystals?
CuO + H^2O + H^2SO^4 = CuSO^4 .5H^2O
7. In the following reactions calculate the mass of precipitate formed from 20 g of the metal salt in each case.
a. ZnSO^4 (aq) + 2NaOH → Zn(OH)^2(s) + Na^2SO^4(aq)
b. Al^2 (SO^4 ) 3(aq) + 6NaOH → 2Al(OH)^3(s) + 3Na^2SO^4(aq)
c. MgSO^4(aq) + 2NaOH → Mg(OH)^2(s) + Na^2^SO^4(aq)
Answer:
3. The mass of ethanol required is approximately 0.522869 g
The mass of ethanoic acid required is approximately 0.68156 g
4. The mass of iron (III) oxide required is approximately 285.952.189.095 tonnes
5. The mass of silver nitrate required is approximately 14.53 grams
6. The mass of copper oxide that would be needed is approximately 31.86 grams
7. a. The mass of the precipitate, Zn(OH)₂ formed is approximately 49.712 grams
b. The mass of the precipitate, Al(OH)₃ formed is approximately 13 grams
c. The mass of the precipitate, Mg(OH)₂, formed is approximately 14.579925 grams
Explanation:
3. The 1 mole of ethanol and 1 mole of ethanoic acid combines to form 1 mole of ethyl ethanoate
The number of moles of ethyl ethanoate in 1 gram of ethyl ethanoate, n = 1 g/(88.11 g/mol) = 1/88.11 moles
∴ The number of moles of ethanol = 1/88.11 moles
The number of moles of ethanoic acid = 1/88.11 moles
The mass of ethanol = (46.07 g/mol) × 1/88.11 moles = 0.522869 g
The mass of ethanoic acid in the reaction = 60.052 g/mol × 1/88.11 moles ≈ 0.68156 g
4. 1 mole of iron(III) oxide reacts with 1 mole of CO₂ to produce 1 mole of iron
The number of moles in 100 tonnes of iron= 100000000/55.845 = 1790670.60614 moles
The mass of iron (III) oxide required = 159.69 × 1790670.60614 = 285952189.095 g ≈ 285.952.189.095 tonnes
5. The number of moles of NaCl in 5 grams of NaCl = 5 g/58.44 g/mol = 0.0855578371 moles
The mass of silver nitrate required, m = 169.87 g/mol × 0.0855578371 moles ≈ 14.53 grams
6. The number of moles of CuSO₄·5H₂O in 100 g of CuSO₄·5H₂O = 100 g/(249.69 g/mol) ≈ 0.4005 moles
The mass of copper oxide required, m = 79.545 g/mol × 0.4005 moles ≈ 31.86 grams
7. a. The number of moles of NaOH in the reaction = 20 g/(39.997 g/mol) ≈ 0.5 moles
2 moles of NaOH produces 1 mole of Zn(OH)₂
0.5 moles of NaOH will produce 0.5 mole of Zn(OH)₂
The mass of 0.5 mole of Zn(OH)₂ = 0.5 mole × 99.424 g/mol = 49.712 grams
The mass of the precipitate, Zn(OH)₂ formed = 49.712 grams
b. 6 moles of NaOH produces 2 moles Al(OH)₃
20 g, or 0.5 mole of NaOH will produce (1/6) mole of Al(OH)₃
The mass of the precipitate, Al(OH)₃ formed, m = 78 g/mol×(1/6) moles = 13 grams
c. 2 moles of NaOH produces 1 mole of Mg(OH)₂, therefore;
20 g or 0.5 moles of NaOH formed (1/4) mole of Mg(OH)₂
The mass of the precipitate, Mg(OH)₂, formed, m = 58.3197 g/mol × (1/4) moles = 14.579925 grams
Answer:
Explanation:
i will show in details how 2 do the 1st Q n u can do the rest by following the way how it is done
3. given C^2H^5OH + CH^3CO^2H → CH^3CO^2C^2H^5 + H^2O
molar ratio of ethanol, ethanoic acid and ethyl ethanoate is 1 : 1 : 1
so mass = no. of moles * molecular mass
for same no. of moles, mass / molecular mass is the same
molecular mass of CH^3CO^2C^2H^5 = 12+1*3+12+16*2+12*2+5*1 = 88
molecular mass of C^2H^5OH = 12*2+1*5+16+1 = 46
molecular mass of CH^3CO^2H = 12+1*3+12+16*2+1 = 60
1 g of ethyl ethanoate = 1/88 mole
it requires 1/88*46 = 0.5227 g of ethanol; and
1/88*60 = 0.6818 g of ethanoic acid
to react together to form 1 g of ethyl ethanoate
what would happen if you boil a substance in an alcohol
Answer:
When a mixture of water and alcohol boils, the vapors are a mixture of water vapor and alcohol vapor
the liquid left after crystallization is
Answer:
The liquid left after crystallization is called Residue
Pleaseeeeeeee Help ASAP!!
Formula of xenon trioxide = XeO3
Relative atomic mass: Xe = 131.29, O = 16
Question 1
number of moles = mass / molar mass
n of XeO3 = 9.07 / 131.29 + 3(16)
= 0.05059 mol
number of moles = number of particle / Alvagadro's constant
0.05059 = number of molecule / 6.02 x 10²³
number of molecules = 3.046 x 10²²
Question 2
number of moles = number of particle / Alvagadro's constant
number of moles = 3.22 x 10²² / 6.02 x 10²³
number of moles = 0.05349 mol
number of moles = mass / molar mass
0.05349 = mass / 131.29 + 3(16)
mass = 9.590g
ayuda, ayuda, ayuda urgente tengo 5 minutos necesito el nombre de lo que viene en las imágenes
Answer:huh
Explanation:
How many ATOMS of boron are present in 3.61 grams of boron trifluoride ?
Answer:
To determine the number of atoms of Boron that are present within 3.61 grams of Boron Trifluoride, it would be best to convert the grams to moles of the compound and then after that use the Avogadro's number to determine the number of molecules and then use the 1 to 3 ratio to determine the total number of Boron atoms.
Which option best describes the water cycle?
El fluoruro de hidrógeno HF que se utiliza en
la obtención de los freones (los cuales
destruyen la capa de ozono de la
estratosfera), se prepara mediante la
siguiente reacción: CaF2 + H2SO4
CaSO4 + 2HF Si se hacen reaccionar 50gr
de CaF2 con 100 gr de H2SO4 (masas
atómicas Ca=40,F=19, H=1, S=32, O=16)
Answer:
25.6g de HF son producidos
Explanation:
...¿Cuánto HF es producido?
Para resolver este problema debemos convertir la masa de cada reactivo a moles usando su masa molar. Como la reacción es 1:1, el reactivo con menor número de moles es el reactivo limitante. Con las moles del reactivo limitante podemos obtener las moles de HF y su masa así:
Moles CaF2:
Masa molar:
1Ca = 40g/mol
2F = 19*2 = 38g/mol
40+38 = 78g/mol
50g CaF2 * (1mol/78g) = 0.641 moles CaF2
Moles H2SO4:
Masa molar:
2H = 2g/mol
1S = 32g/mol
4O = 64g/mol
98g/mol
100g H2SO4 * (1mol / 98g) = 1.02 moles H2SO4
Como las moles de CaF2 < Moles H2SO4: CaF2 es reactivo limitante.
Moles HF usando la reacción:
0.641 moles CaF2 * (2mol HF / 1mol CaF2) = 1.282 moles HF
Masa HF:
Masa molar:
1g/mol + 19g/mol = 20g/mol
1.282 moles HF * (20g/mol) =
25.6g de HF son producidosWhat is the net ionic equation for the following? :)
1. Mg (s) + Na2CrO4 (aq) -->
2. K (s) + Cd(NO3)2 (aq) -->
Answer:
1. Mg (s) + 2Na+(aq) → 2Na(s) + Mg²⁺(aq)
2. 2K(s) + Cd²⁺(aq) → 2K⁺(aq) + Cd(s)
Explanation:
The net ionic equation of a reaction express only the chemical species that are involved in the reaction:
1. Mg (s) + Na2CrO4 (aq) → 2Na + MgCrO4(aq)
The ionic equation:
Mg (s) + 2Na+(aq) + CrO4²⁻ (aq) → 2Na + Mg²⁺ + CrO4²⁻(aq)
Subtracting the ions that don't change:
Mg (s) + 2Na+(aq) → 2Na + Mg²⁺
2. 2K(s) + Cd(NO3)2(aq) → 2KNO3(aq) + Cd(s)
The ionic equation:
2K(s) + Cd²⁺(aq) + 2NO3⁻(aq) → 2K⁺(aq) + 2NO3⁻(aq) + Cd(s)
Subtracting the ions that don't change:
2K(s) + Cd²⁺(aq) → 2K⁺(aq) + Cd(s)Match the reaction to the type that best describes it.
2HCl → H2 + Cl2
?
Combination
NaF + KBr →
NaBr + KE
?
Decomposition
Mg + MnCl2 →
-Mn + MgCl2
?
Single replacement
2Na + 02 →
Na2O2
?
Double replacement
Answer:
2HCl → H2 + Cl2 = decomposition
NaF + KBr → NaBr + KF = double replacement
Mg + MnCl2 → Mn + MgCl2 = single replacement
2Na + 02 → Na2O2 = combination
Explanation:
A chemical reaction involves the conversion of one or more substances called REACTANTS into other substances called PRODUCTS. There are different types of reactions depending on how it occurs, they include:
- Combination or synthesis reaction is a type of reaction in which two or more elements combine to form a single product. Example is:
2Na + 02 → Na2O2
- Single replacement is a type of reaction where one element is replaced by another in a compound or molecule. Example below shows that Manganese (Mn) is replaced by magnesium (Mg):
Mg + MnCl2 → Mn + MgCl2
- Double replacement is a type of reaction where two elements are replaced by other elements at a time. Example is:
NaF + KBr → NaBr + KF
- Decomposition is a type of reaction in which one molecule or compound is broken down into two or more products. Example is:
2HCl → H2 + Cl2
Interms of air molecules, what gives a balloon its shape when air is blown into it
Answer: Because when you blow air /gas into a balloon you fill it with air particles ,so they more you blow u blow in more air particles so they tend to collide with each other ,so as they hit the walls of the balloons pressure is exerted ,so the pressure keeps the balloon inflated with its shape
In the periodic table, identify the element X on its average atomic mass
Answer:
Potassium
Explanation:
To solve this question we need to find, as first, the average atomic mass of the element knowing that is defined as the sum of the masses of each isotope times their abundances. For the element X:
Average atomic mass:
38*0.0967 + 39*0.7868 + 40*0.1134 + 41*0.0031
= 39.02g/mol
The atom that has the average atomic mass closest to 39.02g/mol is Potassium, K = 39.10g/mol.
3. Which of the following is a property of a metal?
A. brittle
B. bendable
C. poor conductor of heat and electricity
D. usually dull in appearance
Answer:
the answer would be d. usually dull in appearance
Explanation:
because brittle bendable and poor conductor of heat and electricity are all for the non-metals
Answer:
C !!
Explanation:
hope this helps! usually people classify metals based on if they can conduct heat or electricity
Why does it stop expanding when you stop blowing air into it
Answer:
this is because of collisions of molecules present in that particular system.
Explanation:
For instance, when air is filled in a balloon then the number of the molecules of air inside the balloon increases. As a result more collisions of molecules take place with the walls. This gives rise to high air pressure on the walls which causes the balloon to expand and get inflated.