Answer:
b. each orbit has a specific energy level
Explanation:
edge
Fossils of a dinosaurs would most likely be found in
A)
conglomerate rock
B) sedimentary rock
C)
Igneous rock
D)
metamorphic rock
Answer:
b
Explanation:
Answer:
B
Explanation:
How many grams of solid sodium cyanide should be added to 1.00 L of a 0.119 M hydrocyanic acid solution to prepare a buffer with a pH of 8.809
Answer:
1.62 g
Explanation:
Given that:
Concentration of HCN = 0.119 M
Assuming the ka 4.00 × 10⁻¹⁰
The pKa of HCN (hydrocyanic acid) = -log (Ka)
= - log ( 4.00 × 10⁻¹⁰)
= 9.398
pH of buffer = 8.809
Using Henderson Hasselbach equation:
[tex]pH = pKa + log \dfrac{[conjugate\ base ]}{acid}[/tex]
[tex]pH = pKa + log \dfrac{[CN^-]}{[HCN]}[/tex]
[tex]8.809 = 9.398 +log \dfrac{[CN^-]}{[HCN]}[/tex]
[tex]log \dfrac{[CN^-]}{[HCN]}= 8.809 - 9.398[/tex]
[tex]log \dfrac{[CN^-]}{[HCN]}= -0.589[/tex]
[tex]\dfrac{[CN^-]}{[HCN]}= 0.2576[/tex]
[CN^-] = 0.2576[HCN]
[CN^-] = 0.2756 (0.119) L
[CN^-] = 0.033 M
∴
The amount of NaCN (sodium cyanide) is calculated as follows:
[tex]= 1.00 L \times \dfrac{0.033 \ mol \ NacN }{1 \ L } \times \dfrac{49.01 \ g}{1 \ mol \ of \ NacN}[/tex]
= 1.62 g
Type the correct answer in the box.
Calculate the density of the substance.
A sample of a substance has a mass of 27.3 grams and a volume of 7.0 centimeters3. The density of this substance is ____
grams/centimeter3.
Answer:
3.9g/cm3
Explanation:
Density ( d)=?
Mass(m)=27.3g
Volume (v)=7.0cm3
D=m÷v
D=27.3g÷7.0cm3
D=3.9g/cm3
Which of the following reasons explains why if salt water is heated, the water turns into steam while the salt remains?
Water and salt have an equal boiling point.
Water has a lower boiling point than salt.
Salt has a lower boiling point than water.
Salt and water have an equal melting point.
If the salt water is heated, the water turns into steam and the salt remains because the water has a lower boiling point than the salt.
The following points can be considered:
The boiling point is defined as the temperature at which the substance turns into the gaseous state from the liquid state.The boiling point of water is [tex]100^{o} C[/tex].The salt is a substance comprising two entities separated by the opposite charges with ionic interactions.The boiling point of a salt is higher than the boiling point of the water.The process involved when salt water is heated:
The salt water mixture when heated, the water turns into steam at [tex]100^{o} C[/tex]But the salt remains until it reaches its boiling temperature. If the salt is soluble in water and is then heated, then there occurs an elevation in the boiling point of the substance, due to the presence of the salt.Therefore, the answer is water has a lower boiling point than salt.
Learn more about salt:
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Which one is the dependent variable in distance, force, or work
Answer:
Work
Explanation:
Formula for work is given by;
Work = force × distance.
It is clear from this formula that Work depends on force and distance.
This means that force and distance are independent of the workdone and so they are classified as independent variables while work will be the dependent variable.
Describe why corrosion is a natural process
Answer :
Answer :because it happens due to moisture and oxygenThe products in a decomposition reaction _____. are compounds can be elements or compounds are elements include an element and a compound
Answer:
compounds are elements include an element and a compound
Explanation:
elements in the decomposition reaction is the substance that cannot be separated into simpler substances. Compounds, technically act as a reactant in the decomposition reaction, but since the reaction breakdown one substance into two or more, sometimes it exists in the product
An OH group attached to a hydrocarbon is called a _________ group whereas ______________ is a polyatomic ion with a charge of _______.
An OH group attached to a hydrocarbon is called an alkyl group whereas hydroxide is a polyatomic ion with a charge of -1.
What is OH group?OH group is also called hydroxyl group. Alcohol is a type of organic compound that is characterized by one or more hydroxyl (―OH) groups attached to a carbon atom of an hydrocarbon chain so we can conclude that an OH group attached to a hydrocarbon is called an alkyl group whereas hydroxide is a polyatomic ion with a charge of -1.
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Using Hess’s law, what is the standard enthalpy of formation of manganese (II) oxide, MnO(s)?
With the help of hess's law:
ΔHf(MnO)=−248.9 kJ−12(272.0) kJ=−384.9 kJ(per mole) Δ H f ( M n O ) = − 248.9 k J − 1 2 ( 272.0 ) k J = − 384.9 k J ( p e r m o l e )
What is Hess's law?Hess's law of constant heat summation, also known simply as Hess' law, is a relationship in physical chemistry named after Germain Hess, a Swiss-born Russian chemist and physician who published it in 1840.
Moreover, hess's Law of Constant Heat Summation (or just Hess's Law) states that regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes.
Therefore, hess' law is based on the state function character of enthalpy and the first law of thermodynamics. Energy (enthalpy) of a system (molecule) is a state function.
Learn more about hess's law:
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Draw the product formed when diene and dienophile react in a Diels–Alder reaction.
Answer:
Explanation:
Diels-Alder reactions are cyclo-additional reactions between conjugated dienes and a dienophile (a substituted alkene compound for example acrylic acid) to produce a ring structure of cyclohexene compounds.
From the image attached below, we will see the reaction between 2,3-dimethylbuta-1,3-diene which is a conjugated diene with acrylic acid to produce a Diel-Alder adduct as the product. From the reaction, a single new π-bond and two σ-bonds are produced.
A student measures her computer keyboard with a meter stick and finds that it has a width of 47.35 cm. Which statement about this measurement is true?
PLZZZZ HELP
A.) All the numbers are certain
B.) The 4 is uncertain
C.) The 5 is somewhat uncertain
D.) The 5 is certain
How is the atomic mass of an element calculated?
Answer:
Mass number (A) is the number of nucleons (proton and neutron) present in a atom.
Explanation:
electrons don't cout since they are thousandth's of the mass of protons or neutrons
Complete the sentence.
Hexene would have _ carbon atoms and one _ bond
First blank options:
7, 8, 1, 2, 4, 3, 5, 6
Second blank options:
single, double, triple
Answer:
6, double
Explanation:
Hex- is a prefix for number 6.
Ene- is a suffix for a double bond.
Write the bond line formula for the compound (CH3)2CHCH2C(CH3)3.
Formula is (CH3)2CHCH2C(CH3)3 and the name is 2,2,4-trimethylpentane
If this experiment was performed again, but this time, 5.0 g of the mixture were used, then, assuming the same mass percentages (5 % cellulose, 47.5 % caffeine, and 47.5 % benzoic acid), what is the theoretical mass (in g) of cellulose in this mixture
Answer:
the theoretical mass of cellulose in this mixture is 0.25 grams
Explanation:
Given the data in the question;
mass of the mixture = 5.0 gram
mass percentage of cellulose = 5%
mass percentage of caffeine = 47.5%
mass percentage of benzoic acid = 47.5%
so mass of caffeine in the mixture will be;
⇒ ( mass percentage of cellulose ) × ( mass of the mixture )
= 5% × 5.0 gram
= ( 5 / 100 ) × 5.0 grams
= 0.05 × 5.0 grams
= 0.25 grams
Therefore, the theoretical mass of cellulose in this mixture is 0.25 grams
examples of isotones
Answer:
Examples of isotones include carbon-12, nitrogen-13 and oxygen-14. These atoms all have six neutrons and six, seven and eight protons respectively. A mnemonic that can be used to differentiate isotones from isotopes and isobars is as follows: same Z (number of protons) = isotopes.
B. It shifts the equilibrium toward the right, favoring product.
11. What is meant by the term heat of reaction?
A. the difference in temperature between products and reactants
B. the difference in bond energies between products and reactants
C. the difference in heat energies between products and reactants
What other name is a synonym for this term?
A. entropy change
B. potential change
C. enthalpy change
Answer:
11) the difference in heat energies between products and reactants
12) enthalpy change
Explanation:
The heat of reaction is defined as that energy released or absorbed as chemical substances participate in a chemical reaction. It is a term used to denote the change in energy as reactants change into products.
Another name of heat of reaction is enthalpy of reaction. It is a state function since it depends on the initial and final states of the system.
what is the scientific name of lion
Answer:
the scientific name of lion is
Panthera leo
I need information about
"forming colloid"
THANK YOU!
Answer:
Condensation methods from colloidal particles by aggregation of molecules or ions. Examples of colloids are really in common in evryday life, eg. Mayonnaise, butter, milk, gelatin, paper etc..
Every colloid consists of two parts :colloidal particles and the dispersing medium.
Describe what happens between the valence electrons in an Ionic Bond.
How is that different from a covalent bond?
Answer:
In an ionic bond, the elctrons are transferred. For example, NaCl has an ionic bond because Na loses an electron and the Cl atom gains the electron. However in a covalent bond, the electrons are shared equally. Covalent bonds usually occur between two nonmetals.
Explanation:
One mole of
C
2
H
6
O
C
2
H
6
O has two moles of Carbon (C), six moles of Hydrogen (H) and one mole of Oxygen (O). How many moles of Hydrogen is in 0.2 moles of
C
2
H
6
O
C
2
H
6
O?
Answer:
c
no need to thank me okay
Draw the predominant product(s) of the following reactions including stereochemistry when it is appropriate. CH3CH2 C C CH3 H2O/H2SO4/HgSO4
Answer:
Draw the predominant product(s) of the following reactions including stereochemistry when it is appropriate.
CH3CH2 C C CH3 H2O/H2SO4/HgSO4
Explanation:
The given compound is: pent-2-yne.
When it reacts with water, in presence of sulphuric acid and mercuric sulphate then a ketone is formed as shown below:
This reaction is an example of nucleophilic attack of water on carbon carbon triple bond.
The general mechanism of the reaction is hsown below:
Pent-2-yne reacts with water and form 3-pentanone.
The reaction is shown below:
For a particular first-order reaction, it takes 48 minutes for the concentration of the reactant to decrease to 25% of its initial value. What is the value for rate constant (in s -1) for the reaction
Answer: The value for rate constant for a reaction is [tex]4.81\times 10^{-4} s^{-1}[/tex]
Explanation:
The integrated rate law equation for first-order kinetics:
[tex]k=\frac{2.303}{t}\log \frac{a}{a-x}[/tex] ......(1)
Let the initial concentration of reactant be 100 g
Given values:
a = initial concentration of reactant = 100 g
a - x = concentration of reactant left after time 't' = 25 % of a = 25 g
t = time period = 48 min = 2880 s (Conversion factor: 1 min = 60 s)
Putting values in equation 1:
[tex]k=\frac{2.303}{2880s}\log (\frac{100}{25})\\\\k=4.81\times 10^{-4} s^{-1}[/tex]
Hence, the value for rate constant for a reaction is [tex]4.81\times 10^{-4} s^{-1}[/tex]
(A) Calculate the wavelength (in nm) of light with energy 1.89 × 10–20 J per photon, (b) For light of wavelength 410 nm, calculate the number of photons per joule, (c) Determine the binding energy (in eV) of a metal if the kinetic energy possessed by an ejected electron [using one of the photons in part (b)] is 2.93 × 10–19 J.
Answer:
For A: The wavelength of the light is [tex]1.052\times 10^4nm[/tex]
For B: The number of photons per joule is [tex]2.063\times 10^{18}[/tex]
For C: The binding energy of a metal is 1.197 eV.
Explanation:
The equation used to calculate the energy of a photon follows:
[tex]E=\frac{hc}{\lambda}[/tex] ......(1)
where,
E = energy of a photon
h = Planck's constant = [tex]6.626\times 10^{-34}J.s[/tex]
c = speed of light = [tex]3\times 10^{8}m/s[/tex]
[tex]\lambda[/tex] = wavelength
For A:Given values:
E = [tex]1.89\times 10^{-20}J[/tex]
Putting values in equation 1, we get:
[tex]\lambda=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{1.89\times 10^{-20}J}\\\\\lambda=1.052\times 10^{-5}m[/tex]
Converting the wavelength into nanometers, the conversion factor used is:
[tex]1m=10^9nm[/tex]
So, [tex]\lambda=1.052\times 10^{-5}m\times \frac{10^9nm}{1m}=1.052\times 10^4nm[/tex]
Hence, the wavelength of the light is [tex]1.052\times 10^4nm[/tex]
For B:Given values:
[tex]\lambda=410nm=410\times 10^{-9}m[/tex]
Putting values in equation 1, we get:
[tex]E=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{410\times 10^{-9}m}\\\\E=4.848\times 10^{-19}J[/tex]
To calculate the number of photons, we use the equation:
[tex]\text{Number of photons}=\frac{\text{Total energy}}{\text{Energy of a photon}}[/tex]
Total energy = 1 J
Energy of a photon = [tex]4.848\times 10^{-19}J[/tex]
Putting values in the above equation:
[tex]\text{Number of photons}=\frac{1J}{4.848\times 10^{-19}J}\\\\\text{Number of photons}=2.063\times 10^{18}[/tex]
Hence, the number of photons per joule is [tex]2.063\times 10^{18}[/tex]
For C:To calculate the binding energy of a metal, we use the equation:
[tex]E=K+B[/tex] .....(2)
E = Total energy
K = Kinetic energy of a photon
B = Binding energy of metal
Converting the energy from joules to eV, the conversion factor used is:
[tex]1eV=1.602\times 10^{-19}J[/tex]
Using the above conversion factor:
[tex]K=2.93\times 10^{-19}J=1.829eV\\\\E=4.848\times 10^{-19}J=3.026eV[/tex]
Putting values in equation 2:
[tex]B=(3.026-1.829)eV=1.197eV[/tex]
Hence, the binding energy of a metal is 1.197 eV.
separete the ALKALI from the following bases :
NH4OH(ammonium nitrate)
CuO(copper oxide)
Zn(OH)2 (zinc hydroxide)
MgO(magnesium oxide)
Na2O(sodium oxide)
NaOH(sodium hydroxide)
CoO(cobalt oxide)
Mg(OH)2(magnesium hydroxide)
LIOH(lithium hydroxide)
help me with this i will surely mark u as Brainliest
plss help!!!
Answer:
Ammonium hydroxide, NH₄OH
Magnesium hydroxide, Mg(OH)₂
Sodium hydroxide, NaOH
Lithium hydroxide, LiOH
Explanation:
A base is a substance which neutralizes acids to produce salt and water. Bases are hydroxide or oxides of metals. Bases may be soluble or insoluble in water. Bases generally have a bitter taste and turn red litmus paper or indicator red.
Alkalis are bases which are soluble in water. They form the hydroxide of the alkali metals or alkaline earth metals in solution and they ionize to produce hydroxide ions. They are slippery to touch and turn red litmus blue being bases.
Therefore, all alkalis are bases but not all bases are alkalis. Insoluble bases are not alkalis.
From the given chemical compounds the alkalis present in the list are:
Ammonium hydroxide, NH₄OH; since it is soluble in water and produces hydroxide ions
Magnesium hydroxide, Mg(OH)₂; since it is slightly soluble in water and produces hydroxide ions
Sodium hydroxide, NaOH; since it is soluble in water and produces hydroxide ions
Lithium hydroxide, LiOH; since it is soluble in water and produces hydroxide ions
CuO(copper oxide) is a base but not an alkali as it does not produce hydroxide ions.
Zn(OH)2 (zinc hydroxide) is amphoteric and is insoluble
MgO(magnesium oxide) is a base but not an alkali as it does not produce hydroxide ions.
Na2O(sodium oxide) is a base but not an alkali as it does not produce hydroxide ions.
CoO(cobalt oxide) is a base but not an alkali as it does not produce hydroxide ions.
Calculate the number of molecules of carbon (IV) oxide
produced when 10g of CaCO3 is treated with 100cm of
0.2mol dm HCl. The equation of the reaction is
CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(1) + CO2(g)
ICa=40 (=12 O=161
Answer: The mass of [tex]CO_2[/tex] produced is 0.44 g
Explanation:
For calcium carbonate:The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
Given mass of calcium carbonate = 10 g
Molar mass of calcium carbonate = 100 g/mol
Plugging values in equation 1:
[tex]\text{Moles of calcium carbonate}=\frac{10g}{100g/mol}=0.1 mol[/tex]
For HCl:The formula used to calculate molarity:
[tex]\text{Molarity of solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (mL)}}[/tex] .....(2)
Molarity of HCl = [tex]0.2mol/dm^3=0.2mol/L[/tex] (Conversion factor: [tex]1L=1dm^3[/tex]
Volume of solution = [tex]100cm^3=100mL[/tex] (Conversion factor: [tex]1mL=1cm^3[/tex]
Putting values in equation 2, we get:
[tex]0.2=\frac{\text{Moles of HCl}\times 1000}{100}\\\\\text{Moles of HCl}=\frac{0.2\times 100}{1000}=0.02mol[/tex]
For the given chemical reaction:
[tex]CaCO_3(s)+2HCl(aq)\rightarrow CaCl_2(aq)+H_2O(l)+CO_2(g)[/tex]
By stoichiometry of the reaction:
If 2 moles of HCl reacts with 1 mole of calcium carbonate
So, 0.02 moles of HCl will react with = [tex]\frac{1}{2}\times 0.02=0.01mol[/tex] of calcium carbonate
As the given amount of calcium carbonate is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.
Thus, HCl is considered a limiting reagent because it limits the formation of the product.
By the stoichiometry of the reaction:
If 2 moles of [tex]HCl[/tex] produces 1 mole of [tex]CO_2[/tex]
So, 0.02 moles of [tex]HCl[/tex] will produce = [tex]\frac{1}{2}\times 0.02=0.01mol[/tex] of [tex]CO_2[/tex]
We know, molar mass of [tex]CO_2[/tex] = 44 g/mol
Putting values in equation 1, we get:
[tex]\text{Mass of }CO_2=(0.01mol\times 44g/mol)=0.44g[/tex]
Hence, the mass of [tex]CO_2[/tex] produced is 0.44 g
0.159 mol 2.25 M = A L of HCI
Answer:
hmmm?what?
Explanation:
ayusin mo flece:>
At 900 oC, Kp = 1.04 for the reactionCaCO31(s) arrow CaO (s) + CO2 (g)At a low temperature, dry ice (solid CO2), calcium oxide, and calcium carbonate are introduced into a 50.0-L reaction chamber. The temperature is raised to 900 oC, resulting in the dry ice converting to gaseous CO2. For the following mixtures, will the initial amount of calcium oxide increase, decrease, or remain the same as the system moves toward equilibrium at 9000 oC?a. 655 gCaCO3, 95.0 gCaO, PCO2 = 2.55 atm.b. 780 gCaCO3, 1.00 gCaO, PCO2 = 1.o4 atm.c. 0.14 gCaCO3, 5000 gCaO,PCO2 = 1.04 atm.d. 715 gCaCO3, 813 gCaO, PCO2 = 0.211 atm.
Answer:
a)the reaction will proceed to the left, the mass of CaO will decrease.
b)the reaction is in equilibrium, mass of CaO will not change.
c)the reaction is in equilibrium, mass of CaO will not change.
d) the reaction will proceed to the right, the mass of CaO will increase.
Explanation:
Step 1: Data given
At 900°C, Kp = 1.04 ( Kp is only for compounds that are in gaseous state)
Volume of the chamber = 50.0L
Temperature is raised to 900 °C
Step 2: The reaction
CaCO31(s) ⇔ CaO (s) + CO2 (g)
Kp for CO2 = 1.04
Step 3: First mix : 655g CaCO3, 95.0g CaO, PCO2 = 2.55 atm
We only consider CO2 here
pCO2 > Kp this means the reaction will proceed to the left, the mass of CaO will decrease.
Step 4: 780g CaCO3, 1.00g CaO, PCO2 = 1.04 atm.
We only consider CO2 here
pCO2 = Kp this means the reaction is in equilibrium, mass of CaO will not change.
Step 5: 0.14g CaCO3, 5000g CaO, PCO2 = 1.04 atm
We only consider CO2 here
pCO2 = Kp this means the reaction is in equilibrium, mass of CaO will not change.
Step 6: 715g CaCO3, 813g CaO, PCO2 = 0.211 atm
We only consider CO2 here
pCO2 < Kp this means the reaction will proceed to the right, the mass of CaO will increase.
The half life for the radioactive decay of potassium-40 to argon-40 is 1.26×109 years. Suppose nuclear chemical analysis shows that there is 0.359 mmol of argon-40 for every 1.000mmol of potassium-40 in a sample of rock. Calculate the age of the rock.
Answer:
2.42x10⁹ years is the age of the rock
Explanation:
The decay of an isotope follows the equation:
Ln[A] = -kt + Ln[A]₀
Where [A] is amount of isotope after time t, k is decay constant and [A]₀ is the initial amount of the isotope
To find decay constant from half-life:
k = ln2 / half-life
k = ln2 / 1.26x10⁹years
k = 5.501x10⁻¹⁰ years⁻¹
As in the reaction, K-40 produce Ar-40:
[A] = 0.359mmol
[A]₀ = 0.359mmol + 1.000mmol = 1.359mmol
Replacing:
Ln[0.359mmol] = -5.501x10⁻¹⁰ years⁻¹t + Ln[1.359mmol]
-1.3312 = -5.501x10⁻¹⁰ years⁻¹t
t = 2.42x10⁹ years is the age of the rock
Nuclear reactions take place inside the nucleus of the atom. Which of the following does NOT represent an everyday example of a nuclear reaction?
Conversion of carbon dioxide and water in photosynthesis
Hydrogen atoms fused together in the Sun
Loss of protons and electrons in plutonium-240 decay
Energy produced by the Sun that is transferred to Earth
Answer:
Loss of protons and electrons in plutonium 240 decay is not an example of an everyday reaction
