Answer:
A. Mass percent composition of oxygen = 58.5%
B. Mass percentage composition of oxygen = 42.1%
C. Mass percentage composition of oxygen = 72.7 %
Explanation:
Percentage mass composition of an element in a compound is given by the formula below:
Percentage mass composition = mass of element/ molar mass of compound × 100%
Percentage mass of oxygen in the given compounds are then calculated.
a. Calcium nitrate, Ca(NO₃)₂: molar mass of compound is obtained first.
Molar mass of Ca(NO₃)₂ = 40 + 14 × 2 + 16 × 2 × 3 = 164 g
Mass of oxygen = 16 × 6 = 96 g
Mass percent composition of oxygen = 96/164 × 100% = 58.5%
b. Iron (ii) sulfate, FeSO₄: molar mass of compound is obtained first.
Molar mass of FeSO₄ = 56 + 32 + 16 × 4 = 152 g
Mass of oxygen = 16 × 4 = 64 g
Mass percentage composition of oxygen = 64/152 × 100% = 42.1%
c. Carbon dioxide, CO₂: molar mass of compound is obtained first.
Molar mass of CO₂ = 12 + 16 × 2 = 44 g
Mass of oxygen = 16 × 2 = 32 g
Mass percentage composition of oxygen = 32/44 × 100% = 72.7 %
What is the pOH of 0.5 M KOH?
Answer:
pOH = 0.3
Explanation:
As KOH is a strong base, the molar concentration of OH⁻ is equal to the molar concentration of the solution. That means that in this case:
[OH⁻] = 0.5 MWith that information in mind we can calculate the pOH by using the following formula:
pOH = -log[OH⁻]pOH = -log(0.5)pOH = 0.3why it is wrong to use the term 'Pure Air' in Science?
Explanation:
Air is a combination of other gases, dust particles, pollens, spores etc. This means that air is a heterogeneous mixture where particles are unevenly distributed.
Air is not considered as a pure substance because there is not one element present in air. A substance which contains only one type of element is called a pure substance.
Therefore, it is wrong to use the term 'Pure Air' in Science.
can yall please help im very slow
Answer:
turtle
Explanation:
they are slow and they take there time
during the process of photosynthesis, green plants produce...
Answer: photosynthesis
Explanation:
Why is the reaction between potassium (K) and chlorine (Cl) considered an oxidation-reduction reaction? (4 points) K(s) + Cl2(g) → 2KCl(s) Select one: a. Chlorine reduces in size when it reacts with potassium. b. Chlorine takes electrons from potassium in the reaction. c. Potassium reduces in strength when it bonds with chlorine. d. Potassium takes chlorine's place in the reaction.
Answer:
(b) Chlorine takes electrons from potassium in the reaction.
Explanation:
Oxidation-Reduction: A reaction in which electrons are exchanged from one substance to another, also called redox.
In K(s) + Cl2(g) → 2KCl(s) , the electrons are being exchanged between one another. In this case, Chlorine atoms are taking electrons from potassium.
you're welcome
The reaction has been termed the oxidation-reduction reaction, as Chlorine takes electrons from potassium. Thus, option C is correct.
The reaction between Chlorine and Potassium has resulted in the formation of Potassium Chloride. The reaction has been termed the ionic redox reaction.
The redox reaction can be described as the oxidation-reduction reaction in which the oxidation of an atom by the loss of electrons, results in the reduction of another atom by the gain of the electron.
In the reaction of Chlorine and Potassium, there has been the loss of electron potassium and the gain of electrons by Chlorine. Thereby Potassium is getting oxidized, and Chlorine is getting reduced.
Thus, the reaction has been termed the oxidation-reduction reaction, as Chlorine takes electrons from potassium. Thus, option C is correct.
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Three acid samples are prepared for titration by 0.01 M NaOH:
1. Sample 1 is prepared by dissolving 0.01 mol of HCl in 50 mL of water.
2. Sample 2 is prepared by dissolving 0.01 mol of HCl in 60 mL of water.
3. Sample 3 is prepared by dissolving 0.01 mol of HCl in 70 mL of water.
a. Without performing a formal calculation, compare the concentrations of the three acid samples (rank them from highest to lowest).
b. When the titration is performed, which sample, if any, will require the largest volume of the 0.01 M NaOH for neutralization?
Guanidine is a neutral compound but is an extremely powerful base. In fact, it is almost as strong a base as a hydroxide ion. Identify which nitrogen atom in guanidine is so basic, and explain why guanidine is a much stronger base than most other amines.
Answer:
See explanation
Explanation:
The molecule called guanidine is shown in the image attached to this answer. It contains three nitrogen atoms. Two among them are sp3 hybridized while one of them is sp2 hybridized.
Guanidine is more basic than other amines because its protonanation leads to the formation of three equivalent resonance structures thereby making its protonated form quite stable. This effect is not observed in other amines.
Also, the sp2 hybridized nitrogen atom is more basic and more easily protonated because when it is protonated, three equivalent resonance structures are obtained.
HELP!!! i will give brainliest!!
Different chemical elements have different chemical symbols, and this is determined by their atomic structure. Look at the two chemical symbols in the image. Compare and contrast the atomic symbols and the atomic structure of fluorine and oxygen.
Answer:
Explanation:
fluorine have gained one electron that is why the sign is -1. they both have different number of protons. They have different neutron numbers. F have 10 and O have 8.
hope this helps :)
What happens to milk when it is poured from a rectangular container into a round glass? (2 points)
Group of answer choices
The milk changes state from a liquid to a solid in the round glass.
The volume of the milk increases when it is poured into a round glass.
The volume of the milk decreases when it is poured into a round glass.
The milk takes the shape of the round glass.
Answer:
The milk takes shape of the round glass.
QUESTIONS :
1.
Many of the flavours and smells of fruits are esters. A learner prepared an ester with a sme
Ilke banana in the school laboratory using pentanol and ethanoic acid. She set up the
apparatus as shown in the diagram below.
PAPER TOWEL DIPPED
-WATER BATH
IN COLD WATER
PEITANOL ETHANOIC
ACID+ 4 DROPS OF
SULPHURIC ACID
1.1 Which property of sulphuric acid makes it suitable to use as a catalyst for the
preparation of esters?
1.2 Why do we heat the test tube in a water bath and not directly over a flame?
1.3 With reference to the characteristic smells of esters, name TWO examples where
esters are used in different industries.
1.4 State ONE function of the wet paper towel in the opening of the test tube.
1.5 Write down the IUPAC name of an ester fomed.
Answer:
See explanation
Explanation:
Esterification is a reaction that involves the combination of an alkanoic acid and an alkanol. The product is always a sweet smelling substance.
Sulphuric acid acts as a catalyst in this reaction because it is a dehydrating agent thereby pushing the equilibrium position towards the right by the removal of water molecules.
The test tubs is heated in a water bath and not directly moved the flame because the alcohol is flammable. Also heating in a water bath helps to separate the reaction mixture from the newly formed ester.
Esters are used in industries that produces soaps and perfumes. There is a great need for the use of fragrances which are ester compounds in these industries.
The wet paper towel in the opening of the test tube cools the top of the test tube. It usually serves as a kind of condenser preventing an excess loss of vapour from the reaction mixture.
The reaction of pentanol and ethanoic acid yields pentyl ethanoate according to IUPAC nomenclature.
chemistry please help
A solution containing 1.22 g of a diprotic acid H2CH2O4 (malonic acid)
was titrated with 45.5 mL of NaOH to reach the second equivalence
point. What is the concentration of the NaOH solution? (MW_malonic
acid = 104.06 g/mol)
Answer:
0.515 M
Explanation:
The reaction that takes place is:
H₂CH₂O₄ + 2NaOH → Na₂CH₂O₄ + 2H₂OFirst we convert 1.22 g of malonic acid into moles, using its molar mass:
1.22 g ÷ 104.06 g/mol = 0.01172 molThen we convert 0.01172 malonic acid moles into NaOH moles, using the stoichiometric coefficients of the balanced reaction:
0.01172 mol H₂CH₂O₄ * [tex]\frac{2molNaOH}{1molH_2CH_2O_4}[/tex] = 0.02344 mol NaOHFinally we calculate the concentration of the NaOH solution, using the number of moles and given volume:
Converting 45.5 mL ⇒ 45.5/1000 = 0.0455 L
0.02344 mol / 0.0455 L = 0.515 MIf we have 1.23 mol of NaOH in solution and 0.85 mol of Cl2 gas is available to react, which one is the limiting reactant? Give your reason.
Answer:
NaOH is the limiting reactant.
Explanation:
Hello there!
In this case, since the reaction taking place between sodium hydroxide and chlorine has is:
[tex]NaOH+Cl_2\rightarrow NaCl+NaClO+H_2O[/tex]
Which must be balanced according to the law of conservation of mass:
[tex]2NaOH+Cl_2\rightarrow NaCl+NaClO+H_2O[/tex]
Whereas there is a 2:1 mole ratio of NaOH to Cl2, which means that the moles of the former that are consumed by 0.85 moles of the latter are:
[tex]n_{NaOH}=0.85molCl_2*\frac{2molNaOH}{1molCl_2}\\\\n_{ NaOH}=1.7molNaOH[/tex]
Therefore, since we just have 1.23 moles out of 1.70 moles of NaOH, we infer this is the limiting reactant.
Regards!
HELPP!
how many grams are in 1.50 x 10(24) atoms of copper?
Answer:
2266g
Explanation:
mass = no.of molecules /6.o23*1o(23) * molar mass
molar mass of co2= 44g /mol
1.5 .10^25/6.023 .10^23 =51.5 moles of co2
51.5 .44g/mol =2266 g
1 mole is equal to 6.023 × 10 ²³ molecules. 2266 grams are in 1.50 x 10²⁴ atoms of copper.
What do you mean by mole ?The term mole is defined as the amount of substance of a system which contains as many elementary entities.
One mole of any substance is equal to 6.023 × 10²³ units of that substance such as atoms, molecules, or ions. The number 6.023 × 10²³ is called as Avogadro's number or Avogadro's constant.
The mole concept can be used to convert between mass and number of particles.
mass = number of molecules / 6.023 × 10²³ × molar mass
molar mass of CO2 = 44g /mol
1.5 .10^25 / 6.023 × 10^23
= 51.5 moles of CO2
= 51.5 .44g/mol
= 2266 g
Thus, 2266 grams are in 1.50 x 10²⁴ atoms of copper.
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You have reacted 100.00mL of 1.353M aqueous sulfuric acid with 12.618g of sodium hydroxide solid. If all of the heat generated by this reaction is transferred to a 1.317kg block of copper metal initially at 16.82°C, what is the final temperature of the block of copper metal? (Specific heat of copper = 0.375J/g*°C)
Answer:
70.137 °C
Explanation:
The reaction generated from the question can be expressed as:
[tex]2NaOH_{(s)} + H_2SO_{4(aq)} \to Na_2SO_{4(aq)} +2H_2O_{(l)}[/tex]
The enthalpy reaction:
[tex]\Delta H^0 _{rxn} = \sum \Delta H^0 _{f (products)} - \sum \Delta H^0 _{f (reactants)}[/tex]
[tex]\Delta H^0 _{rxn} =[2 \times \Delta H^0 _f (H_2O) + \Delta H^0 _f (Na_2SO_4) ] -[2 \Delta \times H^0 _f (NaOH) + \Delta H^0 _f (H_2SO_4) ][/tex]
Repacing the values of each compound at standard enthalpy conditions;
[tex]\Delta H^0 _{rxn} =[2 \times -279.4 + (-1384.49)]-[(2\times -418) -913]\ kJ[/tex]
[tex]\Delta H^0 _{rxn} =-194.29 \ kJ[/tex]
no of moles of NaOH = 12.618g/39.99 g/mol
= 0.3155 mol
no of moles of H₂SO₄ = molarity of H₂SO₄ × Volume
= 1.3553 mol/L × 100 × 10⁻³ L
= 0.13553 mol
From the reaction,
1 mol of NaOH = 2 × mol of H₂SO₄
Since mol of NaOH is greater than that of H₂SO₄, then NaOH is the excess reagent and H₂SO₄ is the limiting reactant
∴
1 mol of H₂SO₄ yields = - 194.29 kJ
0.13553 mol of H₂SO₄ will yield;
[tex]= \dfrac{-194.29 \ kJ}{1 \ mol} \times 0.13553 \ mol[/tex]
= -26.332124 kJ
= -26332.12 J
Finally,
Heat(q) = [tex]m_{(copper)} \times C_{(copper)}\times \Delta T[/tex]
26332.12 J = 1.317 × 10³ g × 0.375 J/g°C ×ΔT
26332.12 J = 493.875 J/° C × ΔT
26332.12 / 493.875 = ΔT
ΔT = 53.317 °C
[tex]T_f - T_i = 53.317 ^0 C[/tex]
[tex]T_f[/tex]- 16.82 °C = 53.317 °C
[tex]T_f[/tex] = (53.317 + 16.82) °C
[tex]T_f[/tex] = 70.137 °C
What are fluids? Why are they so called?
Fluids are liquid and gases. They take the shape of their containers. They are called fluids because of their ability to flow.
You dissolve 14 g of Mg(NO3)2 in water and dilute to
750 mL. What is the molarity of this solution?
Answer:
0.127M
Explanation:
Molarity of a solution = number of moles (n) ÷ volume (V)
Molar mass of Mg(NO3)2 = 24 + (14 + 16(3)}2
= 24 + {14 + 48}2
= 24 + 124
= 148g/mol
Using the formula, mole = mass/molar mass, to convert mass of Mg(NO3)2 to mole
mole = 14g ÷ 148g/mol
mole = 0.095mol
Volume = 750mL = 750/1000 = 0.75L
Molarity = 0.095mol ÷ 0.75L
Molarity = 0.127M
Write a word equation for
H2O2 + liver
Answer:
h2o2 and liver produce oxygen gas
Waves are generated when energy passes through causing them to move matter through ____ ?
Answer:
sending heat waves and vibrations
The value of ΔH° for the reaction below is -6535 kJ. ________ kJ of heat are released in the combustion of 16.0 g of C6H6 (l)?
2C6H6 (l) + 15O2 (g) → 12CO2 (g) + 6H2O (l)
Answer:
the value of H° is below -6535 kj. +6H2O
Explanation:
6H2O answer solved
For the given reaction, 2 moles of C₆H₆ the heat energy released is - 6535 KJ. Then, for 16 g of the compound or 0.205 moles needs 669.83 KJ of heat released in combustion.
What is combustion ?Combustion is a chemical reaction that occurs between a fuel and an oxidizing agent, typically oxygen, resulting in the release of heat, light, and various combustion products, such as carbon dioxide and water vapor.
The process of combustion involves a rapid and exothermic (heat-releasing) oxidation reaction that produces a flame, which is visible in many cases.
Here, 2 moles of the hydrocarbon releases - 6535 KJ of energy.
molar mass of C₆H₆ = 78 g/mol
then no.of moles in 16 g = 16 /78 = 0.205 moles.
then energy released by 0.205 moles = 0.205 moles × 6535 KJ /2 moles = 669.83 kJ
Therefore, the heat energy released by 16 g of the compound in combustion is 669.83 kJ.
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What is used to measure P? To measure T? in Gas laws
Answer:
P = pressure T = temperature
You have 100 mL of a solution of benzoic acid in water; the amount of benzoic acid in the solution is estimated to be about 0.30 g. The distribution coefficient of benzoic acid in diethyl ether and water is approximately 10. Calculate the amount of acid that would be left in the water solution after four 20-mL extractions with ether.
Answer:
0.00370 g
Explanation:
From the given information:
To determine the amount of acid remaining using the formula:[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{(initial \ mass \ of \ solute )_{water}} = (\dfrac{v_2}{v_1+v_2\times k_d})^n[/tex]
where;
v_1 = volume of organic solvent = 20-mL
n = numbers of extractions = 4
v_2 = actual volume of water = 100-mL
k_d = distribution coefficient = 10
∴
[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{0.30 \ g} = (\dfrac{100 \ ml}{100 \ ml +20 \ ml \times 10})^4[/tex]
[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{0.30 \ g} = (\dfrac{100 \ ml}{100 \ ml +200 \ ml})^4[/tex]
[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{0.30 \ g} = (\dfrac{1}{3})^4[/tex]
[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{0.30 \ g} = 0.012345[/tex]
Thus, the final amount of acid left in the water = 0.012345 * 0.30
= 0.00370 g
cấu hình electron của nguyên tử Ca
Explanation:
Do đó cấu hình electron của canxi là: 1s2 2s2 2p6 3s2 3p6 4s2.
An unknown organic compound composed of carbon, hydrogen and oxygen was analyzed and found to be 50.84% C, 8.53% H and the rest being oxygen. Which of the following represents the correct empirical formula for the compound?
(a) CH2O
(b) C3H602
(c) C4H803
(d) C2H40
(e) C5H1003
Answer:
e) C5H10O3
Explanation:
According to the information given in this question;
50.84% represents C
8.53% represents H
[100% - (50.84 + 8.53)]
= 100 - 59.37
= 40.63% of Oxygen (O)
This percentage means that;
Carbon = 50.84g
Hydrogen = 8.53g
Oxygen = 40.63g
By dividing by their respective atomic masses, we convert to moles:
C = 50.84g ÷ 12 = 4.24mol
H = 8.53g ÷ 1 = 8.53mol
O = 40.63g ÷ 16 = 2.54mol
Next we divide by the smallest no of the values (2.54mol)
C = 4.24 ÷ 2.54 = 1.669
H = 8.53 ÷ 2.54 = 3.358
O = 2.54 ÷ 2.54 = 1
To get a simple whole number ratio, we multiply the results by 3
C = 1.669 × 3 = 5.007
H = 3.358 × 3 = 10.074
O = 1 × 3 = 3
Simple whole number ratio of carbon, hydrogen and oxygen is 5:10:3. Hence, the empirical formula is C5H10O3.
A sample of oxygen gas occupies a volume of 2.,0cm3 at pressure of 700K pa. what will be pressure of the same sample occupies a volume of 150cm, assume temperature remains constant
Answer:
The pressure will be 933.33 Kpa
Explanation:
Given that:
Volume V₁ = 200 cm³ (note, there is a mistake in the volume. It is supposed to be 200 cm³)
Pressure P₁ = 700 Kpa
Pressure P₂ = ??? (unknown)
Volume V₂ = 150 cm³
Temperature = constant
Using Boyle's law:
PV = constant
i.e.
P₁V₁ = P₂V₂
700 Kpa × 200 cm³ = P₂ × 150 cm³
P₂ = (700 Kpa × 200 cm³)/150 cm³
P₂ = 933.33 Kpa
What happens to an electroscope when a negatively charged rod is brought close to the metal sphere at the top?
Answer:
When the negatively-charged rod is brought close to the electroscope, positive charges are attracted to it and negative charges are repelled away from it. The electroscope has a net neutral charge and the rubber rod has a net negative charge. If they are brought into contact, they will both take a net negative charge.
Explanation:
I looked it up
To determine the freezing point depression of a LiCl solution, Toni adds 0.411 g of LiCl to the sample test tube along with 19.7 mL of distilled water. Determine the molal concentration (m) of the resulting solution. MWLiCl
Answer:
LiCl = 0.492 m
Explanation:
Molal concentration is the one that indicates the moles of solute that are contained in 1kg of solvent.
Our solute is lithium chloride, LiCl.
Our solvent is distilled water.
We do not have the mass of water, but we know the volume, so we should apply density to determine mass.
Density = mass / volume
Density . volume = mass
1 g/mL . 19.7 mL = 19.7 g
We convert g to kg → 19.7 g . 1 kg / 1000g = 0.0197 kg
Let's determine the moles of LiCl
0.411 g . 1 mol / 42.394 g = 9.69×10⁻³ moles
Molal concentration (m) = 9.69×10⁻³ mol / 0.0197 kg → 0.492 m
The molal concentration of the resulting solution is 0.492 m. The concentration number of moles of solute in one kg of solvent.
What is Molal concentration?It is the measure of the concentration number of moles of solute in one kg of solvent.
To calculate the molal concentration first calculated the mass of [tex]\bold {LiCl}[/tex],
[tex]\rm \ mass = density \times volume[/tex]
Put the values,
m = 1 g/mL x 19.7 mL
m = 19.7 g or
m = 0.0197 kg
Calculate the moles of LiCl:
[tex]n =\rm \dfrac { 0.411 \ g \times 1 mol }{ 42.394 \ g }\\\\n = 9.69\times 10^{-3} \ moles[/tex]
So, now the molal concentration,
[tex]m = \rm \dfrac { 9.69\times 10^{-3}\ mol} {0.0197 \ kg} \\\\m = 0.492[/tex]
Therefore, the molal concentration of the resulting solution is 0.492 m.
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All bases dissociate
True or false
Answer:
verdadero
Explanation:
porque esoo [tex]\lim_{n \to \infty} a_n x_{123} \frac{x}{y} \sqrt[n]{x} x^{2} \sqrt{x} \pi \neq \lim_{n \to \infty} a_n \left[\begin{array}{ccc}1&2&3\\4&5&6\\7&8&9\end{array}\right] \int\limits^a_b {x} \, dx \left \{ {{y=2} \atop {x=2}} \right.[/tex]
Chrysanthenone is an unsaturated ketone. If Chrysanthenone has M+ = 150 and contains 2 double bond(s) and 2 ring(s); what is its molecular formula? Enter the formula in the form CH first, then all other atoms in alphabetical order; do not use subscripts. The formula is case-sensitive.
Answer:
the Molecular formula will be; C10H14O
Explanation:
Given the data in the question;
Chrysanthenone is an unsaturated ketone,
it has M+ = 150 and contains 2 double bond(s) and 2 ring(s).
molecular formula = ?
we know that ketone contain 1 oxygen and mass of oxygen is 16
so mass of the C and H remaining will be;
⇒ 150 - 16 = 134
Now we determine the number of C atoms;
⇒ 134 / 13 = 10
hydrocarbon with 10 hydrogen atom have CnH2n+2 means
⇒ ( 10 × 2 ) +2 = 22 hydrogens
But then we have 3 unsaturation meaning 6 hydrogens less and also we have ring meaning 2 more hydrogens
⇒ 22 - 6 - 2 = 14
Hence the Molecular formula will be; C10H14O
Plutonium-238 is a radioactive element that decays over time into a less harmful element at a rate of 0.8 % per year. A power plant has 50 pounds of plutonium-238 to dispose of. How much plutonium-238 will be left after 10 years
Answer:
46 pounds
Explanation:
Let the amount of Plutonium-238 left after 10 years be P
Let the initial mass of Plutonium-238 be Po
Let the rate of decay be r
Let the time taken be t
Hence;
P = Poe^-rt
P= 50e^-0.008×10
P= 46 pounds