Answers
Answer:
Explanation:
Given that:
The argon atoms are excited into an excited state before emitting the 488.0 nm laser.
the energy of the first ionization energy of argon is 1520 kJ mol-1.
SInce 1 eV = 96.49 kJ/mol
Therefore, the energy of the first ionization energy of argon in eV is = ( 1520/ 96.49) eV
= 15.75 eV
To find where the energy level of the excited state lies below the vacuum energy level, let's first determine, the energy liberated by using planck expression.
[tex]E = \dfrac{hc}{\lambda}[/tex]
[tex]E = \dfrac{6.6 \times 10^{-34} \times 3 \times 10^8}{488 \times 10^{-9}}[/tex]
[tex]E = \dfrac{1.98 \times 10^{-25}}{488 \times 10^{-9}}[/tex]
[tex]E = \dfrac{1.98 \times 10^{-25}}{488 \times 10^{-9}}[/tex]
[tex]E =4.057 \times 10^{-19} \ J[/tex]
Converting Joules (J) to eV ; we get,
[tex]E =\dfrac{4.057 \times 10^{-19}}{1.6 \times 10^{-19}}[/tex]
E = 2.53 eV
The energy levels of the first exited state = -13.223 eV
Related Questions
The K sp for silver(I) phosphate is 1.8 × 10 –18. Determine the silver ion concentration in a saturated solution of silver(I) phosphate.
Answers
Answer:
[tex][Ag^+]=4.82x10^{-5}M[/tex]
Explanation:
Hello,
In this case, the dissociation reaction for silver phosphate is:
[tex]Ag_3PO_4(s)\rightleftharpoons 3Ag^+(aq)+PO_4^{3-}(aq)[/tex]
Therefore, the equilibrium expression is:
[tex]Ksp=[Ag^+]^3[PO_4^{3-}][/tex]
And in terms of the reaction extent [tex]x[/tex] is:
[tex]Ksp=1.8x10^{-18}=(3x)^3(x)[/tex]
Thus, [tex]x[/tex] turns out:
[tex]1.8x10^{-18}=27x^4\\\\x=\sqrt[4]{\frac{1.8x10^{-18}}{27} } \\\\x=1.61x10^{-5}M[/tex]
In such a way, the concentration of the silver ion is:
[tex][Ag^+]=3x=3*1.61x10^{-5}M=4.82x10^{-5}M[/tex]
Best regards.
Will a precipitate (ppt) form when 20.0 mL of 1.1 × 10 –3 M Ba(NO 3) 2 are added to 80.0 mL of 8.4 × 10 –4 M Na 2CO 3?
Answers
Answer:
A precipitate will form, BaCO₃
Explanation:
When Ba²⁺ and CO₃²⁻ ions are in an aqueous media, BaCO₃(s), a precipitate, is produced following its Ksp expression:
Ksp = 5.1x10⁻⁹ = [Ba²⁺] [CO₃²⁻]
Where the concentrations of the ions are the concentrations in equilibrium
For actual concentrations of a solution, you can define Q, reaction quotient, as:
Q = [Ba²⁺] [CO₃²⁻]
If Q > Ksp, the ions will react producing BaCO₃, if not, no precipitate will form.
Actual concentrations of Ba²⁺ and CO₃²⁻ are:
[Ba²⁺] = [Ba(NO₃)₂] = 1.1x10⁻³ × (20.0mL / 100.0mL) = 2.2x10⁻⁴M
[CO₃²⁻] = [Na₂CO₃] = 8.4x10⁻⁴ × (80.0mL / 100.0mL) = 6.72x10⁻⁴M
100.0mL is the volume of the mixture of the solutions
Replacing in Q expression:
Q = [Ba²⁺] [CO₃²⁻]
Q = [2.2x10⁻⁴M] [6.72x10⁻⁴M]
Q = 1.5x10⁻⁷
As Q > Ksp
A precipitate will form, BaCO₃
Name four types of salts
Answers
Answer:
Any ionic molecule formed of a base and an acid, which dissolves in water to produce ions is known as a salt. The four common types of salts are:
1. NaCl or sodium chloride is the most common kind of salt known. It is also known as table salt.
2. K2Cr2O7 or potassium dichromate refers to an orange-colored salt formed of chromium, potassium, and oxygen. It is toxic to humans and is also an oxidizer, which is a fire hazard.
3. CaCl2 or calcium chloride looks like table salt due to its white color. It is broadly used to withdraw ice from roads. It is hygroscopic.
4. NaHSO4 or sodium bisulfate produces from hydrogen, sodium, oxygen, and sulfur. It is also known as dry acid. It has commercial applications like reducing the pH of swimming pools and spas and others.
If a reaction is first-order with respect to a particular reactant, when the concentration of that reactant is increased by a factor of 2, the reaction rate will _____.
Answers
Answer:
It would increase by a factor of 2
Explanation:
The rate law for a fist order reaction is given as;
A --> B
rate = k [A]
upon doubling the concentration, we have;
rate = k [A]
rate 2 = k 2 [A]
Dividing both equations;
rate 2 / rate 1 = k 2 [A] / k [A]
rate 2 / rate 1 = 2 / 1
The ratio between rate 2 and rate 1 is 2 : 1. This means that the reaction rate would also increase by a factor of 2.
How many dozen (dz) eggs are needed to make 12 muffins? What about 15.5
muffins? (hint cross out units first) *
Answers
Answer:
I think its 1.2 cause I divided 15.5 with 12 and got 1.2 as an answer
26.0 g of a liquid that has a density of 1.44 g/mL needs to be measured out in a graduated cylinder . What volume should be used
Answers
Answer: The volume of liquid used will be 18.055 mL.
A compound is found to contain 27.29 % carbon and 72.71 % oxygen by weight. To answer the questions, enter the elements in the order presented above. 1. What is the empirical formula for this compound
Answers
Answer:
CO2
Explanation:
Mass of carbon = 27.29
Mass of oxygen = 72.21
Step 1:
We have to first convert these masses to moles
Carbon = 2.29/2.01 = 2.274
Oxygen = 72.71/16 = 4.544
Step 2:
We have to divide the mols by the smallest mol to get simplest ratio of whole number.
The smallest mol is 2.274. we have to divide the mols by this.
2.274/2.274 = 1
4.544/2.274 = 2
Our empirical formula is therefore CO2
NEED HELP ASAP
In 1988, three gray whales were trapped in Arctic ice. Television crews captured the frantic
attempts of hundreds of people to save the whales. Eventually, a Soviet icebreaker and U.S.
National Guard helicopters arrived to help free the whales. The cost of the rescue mission
exceeded $5 million.
i. Write a scientific question related to the whale story. (1 point)
Answers
An oxidation-reduction reaction in which 3 electrons are Transferred has ∆G° = +18.55 kJ at 25°C? What is the value of E°?
Answers
Answer:
The correct answer is: 0.064 V
Explanation:
In a oxidation-reduction reaction, the relation between Gibbs free energy (ΔGº) and cell potential (Eºcell) is given by:
[tex]\Delta G^{0} = -nFE^{0} _{cell}[/tex]
where n is the number of electrons that are transferred in the reaction and F is the Faraday constant (96,500 C/mol e-). Given: ∆G° = +18.55 kJ and n= 3 mol e-, we calculate Eºcell as follows:
+18.55 kJ = (-3 mol e-) x (96500 C/mol e-) x Eºcell
Eºcell= (+18.55 kJ)/(-3 mol e-) x (96500 C/mol e-)
Eºcell= (18550 J)/ (289500 C)
Eºcell= 0.064 J/C
Since 1 Volt= 1 Joule/1 Coulomb, thus:
Eºcell= 0.064 J/C = 0.064 V
You have a saturated solution of BaSO4, a slightly soluble ionic compound. What happens if you add Ba(OH)2, NaNO3, and CuSO4 to this solution
Answers
Answer:
- Addition of Ba(OH)2: favors the formation of a precipitate.
- Undergo a chemical reaction forming soluble species.
- Addition of CuSO4 : favors the formation of a precipitate.
Explanation:
Hello,
In this case, since the dissociation reaction of barium sulfate is:
[tex]BaSO_4(s)\rightleftharpoons Ba^{2+}(aq)+SO_4^{2-}(aq)[/tex]
We must analyze the effect of the common ion:
- By adding barium hydroxide, more barium ions will be added to the equilibrium system so the formation of solid barium sulfate will be favored (reaction shifts leftwards towards reactants).
- By adding sodium nitrate, the following reaction will undergo:
[tex]BaSO_4(s)+NaNO_3(aq)\rightarrow Ba(NO_3)_2(aq)+Na_2SO_4(aq)[/tex]
So the precipitate will turn into other soluble species.
- By adding copper (II) sulfate, more sulfate ions will be added to the equilibrium system so the formation of solid barium sulfate will be favored (reaction shifts leftwards towards reactants).
All of this is supported by the Le Chatelier's principle.
Best regards.
Calculate the solubility of Mg(OH)2 in water at 25 C. You'll find Ksp data in the ALEKS Data tab. Round your answer to significant digits.
Answers
Answer:
1.12 × 10⁻⁴ M
Explanation:
Step 1: Write the reaction for the solution of Mg(OH)₂
Mg(OH)₂(s) ⇄ Mg²⁺(aq) + 2 OH⁻(aq)
Step 2: Make an ICE chart
We can relate the solubility product constant (Ksp) with the solubility (S) through an ICE chart.
Mg(OH)₂(s) ⇄ Mg²⁺(aq) + 2 OH⁻(aq)
I 0 0
C +S +2S
E S 2S
The solubility product constant is:
Ksp = 5.61 × 10⁻¹² = [Mg²⁺] × [OH⁻]² = S × (2S)² = 4S³
S = 1.12 × 10⁻⁴ M
Which of the following elements can't have an expanded octet? answers A. oxygen B. phosphorous C. chlorine d. sulfer
Answers
answer is oxygen .
oxygen is an exception in octet rule
Among the following given elements,oxygen is an element which cannot have an expanded octet.
What is an expanded octet?Expanded octet is a condition where an octet has more than 8 electrons and which is called as hyper-valency state. This concept is related to hybrid orbital theory and Lewis theory. Hyper-valent compounds are not less common and are of equal stability as the compounds which obey octet rule.
Expansion of octet is possible for elements from third period on wards only as they have low-lying empty d - orbitals which can accommodate more than eight electrons.
Expanded octet is not applicable to oxygen as it is second period of periodic table and has less than ten electrons and even does not have the 2d -orbitals due to which it does not fulfill the criteria of an element to have an expanded octet.
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Calculate the amount of heat needed to melt of ice () and bring it to a temperature of . Round your answer to significant digits. Also, be sure your answer contains a unit symbol.
Answers
Answer:
your answer is given below
Explanation:
Take it stepwise, and you are going to have to look up the various heat values.
You have 36.5grams of ice, presumably at 0C. You will need to add heat to take the ice at 0 C to water at 0 C. (Latent heat of melting) Then you add in a different heat value to take the water at 0 C to water at 82.3 C. (Specific heat of water)
Add the two heat amounts together.
According to specific heat capacity, to calculate the amount of heat needed to melt ice given mass of ices is multiplied by specific heat of ice and the temperature change which it undergoes.
What is specific heat capacity?Specific heat capacity is defined as the amount of energy required to raise the temperature of one gram of substance by one degree Celsius. It has units of calories or joules per gram per degree Celsius.
It varies with temperature and is different for each state of matter. Water in the liquid form has the highest specific heat capacity among all common substances .Specific heat capacity of a substance is infinite as it undergoes phase transition ,it is highest for gases and can rise if the gas is allowed to expand.
It is given by the formula ,
Q=mcΔT
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alculate the pH of the solution, upon addition of 0.035 mol of NaOH to the original buffer. Express your answer using two decimal places.
Answers
A 1.0-L buffer solution contains 0.100 mol HC2H3O2 and 0.100 mol NaC2H3O2. The value of Ka for HC2H3O2 is 1.8×10−5.
Calculate the pH of the solution, upon addition of 0.035 mol of NaOH to the original buffer.
Answer:
The pH of this solution = 5.06
Explanation:
Given that:
number of moles of CH3COOH = 0.100 mol
volume of the buffer solution = 1.0 L
number of moles of NaC2H3O2 = 0.100 mol
The objective is to Calculate the pH of the solution, upon addition of 0.035 mol of NaOH to the original buffer.
we know that concentration in mole = Molarity/volume
Then concentration of [CH3COOH] = [tex]\mathtt{ \dfrac{0.100 \ mol}{ 1.0 \ L }}[/tex] = 0.10 M
The chemical equation for this reaction is :
[tex]\mathtt{CH_3COOH + OH^- \to CH_3COO^- + H_2O}[/tex]
The conjugate base is CH3COO⁻
The concentration of the conjugate base [CH3COO⁻] is = [tex]\mathtt{ \dfrac{0.100 \ mol}{ 1.0 \ L }}[/tex]
= 0.10 M
where the pka (acid dissociation constant)for CH3COOH = 4.74
If 0.035 mol of NaOH is added to the original buffer, the concentration of NaOH added will be = [tex]\mathtt{ \dfrac{0.035 \ mol}{ 1.0 \ L }}[/tex] = 0.035 M
The ICE Table for the above reaction can be constructed as follows:
[tex]\mathtt{CH_3COOH \ \ \ + \ \ \ \ OH^- \ \ \to \ \ CH_3COO^- \ \ \ + \ \ \ H_2O}[/tex]
Initial 0.10 0.035 0.10 -
Change -0.035 -0.035 + 0.035 -
Equilibrium 0.065 0 0.135 -
By using Henderson-Hasselbalch equation:
The pH of this solution = pKa + log [tex]\mathtt{\dfrac{CH_3COO^-}{CH_3COOH}}[/tex]
The pH of this solution = 4.74 + log [tex]\mathtt{\dfrac{0.135}{0.065}}[/tex]
The pH of this solution = 4.74 + log (2.076923077 )
The pH of this solution = 4.74 + 0.3174
The pH of this solution = 5.0574
The pH of this solution = 5.06 to two decimal places
Why don't siblings look exactly alike
Answers
Answer:
Your genes play a big role in making you who you are. ... But brothers and sisters don't look exactly alike because everyone (including parents) actually has two copies of most of their genes. And these copies can be different. Parents pass one of their two copies of each of their genes to their kids.
Given that the Ksp value for Ca3(PO4)2 is 8.6×10−19, if the concentration of Ca2+ in solution is 4.9×10−5 M, the concentration of PO3−4 must exceed _____ to generate a precipitate.
Answers
Answer:
.0027 M
Explanation:
We must calculate the threshold concentration of PO3−4 using Ksp and the given concentration of Ca2+:
Ca3(PO4)2(s)⇌3Ca2+(aq)+2PO3−4(aq)
Ksp=8.6×10−19=[Ca2+]3[PO3−4]2=(4.9×10−5M)3[PO3−4]2
[PO3−4]=0.0027 M
A rock has a mass of 15.8 g and causes the water level in a graduated cylinder to raise from 22.3 mL to 32.5 mL. What is the density of the rock in Kg/mL?
Answers
Answer:
Explanation:
mass - 15.8 g = 0.0158 kg
volume = 32.5 - 22.5 = 10.2 ml
density = mass / volume
= 0.0158 / 10.2
= 0.00154 kg/ml
hope this helps
plz mark as brainliest!!!!!!!
What can you learn about the pH of a substance with the conductivity test? hint: gives you no info on concentration.
Answers
Answer:
See explanation
Explanation:
So, I'm gonna take a shot at this one and say this:
With a strongly acidic/basic solution, you'll get a high conductivity when preforming a conductivity test.
The more acidic or basic a substance is, the higher the electrical conductivity.
Based on how high or low the conductivity is, it will give you an idea of the substance's pH.
Hope that made since or gave you an idea of what you're looking for. Good luck :)
When HCl is added to water, the [H3O+] = 0.6 M. What is the [OH-]?
What is the pH of the solution?
Answers
Answer:
pH=0.22.
[tex][OH^-]=1.66x10^{-14}M[/tex]
Explanation:
Hello,
In this case, since the pH is directly computed from the given concentration of hydronium ions:
[tex]pH=-log([H_3O^+])=-log(0.6M)=0.22[/tex]
It is widely known that the pH and POH are directly related via:
[tex]pH+pOH=14[/tex]
Therefore, the pOH is:
[tex]pOH=14-pH\\\\pOH=14-0.22=13.78[/tex]
Thus, the concentration of hydroxyl ions are computed from the pOH:
[tex]pOH=-log([OH^-]}\\\\[/tex]
[tex][OH^-]=10^{-pOH]=10^{-13.78}[/tex]
[tex][OH^-]=1.66x10^{-14}M[/tex]
Regards.
Which of the following ionic lattices would have the highest melting point?
A. Potassium oxide
w
B. Boron nitride
C. Beryllium oxide
D. Lithium chloride
Answers
Answer:
I think, berryllium oxide, is answer.Explanation:
Hope it helps you....The ionic lattices would have the highest melting point Potassium oxide. option A is correct.
what is ionic lattice?An ionic compound is a giant structure of ions. The ions have a regular, repeating arrangement called an ionic lattice. The lattice is formed because the ions attract each other and form a regular pattern with oppositely charged ions next to each other.
Ionic compounds are held together by electrostatic forces between oppositely charged ions.
These forces are usually referred to as the ionic lattice contains such a large number of ions, that a lot of energy is needed to overcome this ionic bonding so ionic compounds have high melting and boiling points.
therefore, sodium oxide has the highest melting point. option A is correct
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What is the change in entropy (AS) when a solid substance decomposes and
produces gaseous products?
Answers
Explanation:
Entropy refers to the degree of disorderliness in a system. Generally solids have a greater degree of order when compared to gas in which the molecules/particles move randomly in all directions.
The change in entropy from solid to gaseous phase is a positive change. Because there is increase disorderliness of the system.
To find the pH of a solution of NH4Br directly, one would need to use:__________
Select the correct answer below:
a) the Kb of NH3 to find the hydroxide concentration
b) the Ka of NH+4 to find the hydronium concentration
c) the Kb of NH3 to find the hydronium concentration
d) the Ka of NH+4 to find the hydroxide concentration
Answers
Answer:
b) the Ka of NH₄⁺ to find the hydronium concentration
Explanation:
The equilbrium of NH₄⁺ (The conjugate acid of NH₃, a weak base), is:
NH₄⁺ ⇄ NH₃ + H⁺
Where Ka of the conjugate acid is:
Ka = [NH₃] [H⁺] / [NH₄⁺]
Thus, if you know Ka of NH₄⁺ and its molar concentration you can calculate [H⁺], the hydronium concentration, to find pH (Because pH = -log [H⁺])
Thus, right option is:
b) the Ka of NH₄⁺ to find the hydronium concentrationSuppose a small amount of a solid is added to water and, after a short time, all the solid has dissolved. Which of the following statements is most likely to be true?
A) The solution is supersaturated with solute.
B) The solution is saturated with solute.
C) The solution is unsaturated with solute.
D) The solution is either unsaturated or supersaturated with solute.
E) The solution is either saturated or supersaturated with solute.
Answers
Answer:
the option e is correct I think
The solution is either saturated or supersaturated with solute
Answer:
the option e is correct I think
The solution is either saturated or supersaturated with solute
Explanation:
For which of the following elements (in their normal, stable, forms) would it be correct to describe the bonding as involving "a sea of electrons"?
a. hydrogen
b. nellum
c. sulfur
d. Iodine
e. Ethium
Answers
Answer:
e. Lithium
Explanation:
Correct list of options!
a. hydrogen b. Helium c. sulfur d. Iodine e. Lithium
Sea of electrons generally refers to metal atoms. This is because of the delocalized nature of the electrons compared to non metals where the electrons are localized (fixed to a specific atoms).
Among all the elements in the options, the metal is option e. Lithium
A laboratory technician combines 35.9 mL of 0.258 M chromium(II) chloride with 35.8 mL 0.338 M potassium hydroxide. How many grams of chromium(II) hydroxide can precipitate
Answers
Answer:
0.52 g of chromium(II) hydroxide, Cr(OH)2.
Explanation:
We'll begin by calculating the number of mole of chromium (ii) chloride, CrCl2 in 35.9 mL of 0.258 M chromium(II) chloride solution.
This can be obtained as follow:
Molarity of CrCl2 = 0.258 M
Volume = 35.9 mL = 35.9/1000 = 0.0359 L
Mole of CrCl2 =?
Molarity = mole /Volume
0.258 = mole of CrCl2 /0.0359
Cross multiply
Mole of CrCl2 = 0.258 x 0.0359
Mole of CrCl2 = 0.0093 mole
Next, we shall determine the number of mole of potassium hydroxide, KOH in 35.8 mL 0.338 M potassium hydroxide solution.
This can be obtained as follow:
Molarity of KOH = 0.338 M
Volume = 35.8 mL = 35.8/1000 = 0.0358 L
Mole of KOH =.?
Molarity = mole /Volume
0.338 = mole of KOH /0.0358
Cross multiply
Mole of KOH = 0.338 x 0.0358
Mole of KOH = 0.0121 mole.
Next, we shall write the balanced equation for the reaction. This is given below:
2KOH + CrCl2 → Cr(OH)2 + 2KCl
From the balanced equation above,
2 mole of KOH reacted with 1 mole of CrCl2 to produce 1 mole of Cr(OH)2.
Next, we shall determine the limiting reactant. This can be obtained as follow:
From the balanced equation above,
2 mole of KOH reacted with 1 mole of CrCl2.
Therefore, 0.0121 mole of KOH will react with = (0.0121 x 1)/2 = 0.00605 mole of CrCl2.
From the calculations made above, we can see that only 0.00605 mole out of 0.0093 mole of CrCl2 is needed to react completely with 0.0121 mole of KOH.
Therefore, KOH is the limiting reactant.
Next, we shall determine the number of mole of Cr(OH)2 produced from the reaction.
In this case, we shall be using the limiting reactant because it will give the maximum yield of Cr(OH)2.
The limiting reactant is KOH and the number of mole of Cr(OH)2 produced can be obtained as illustrated below:
From the balanced equation above,
2 mole of KOH reacted to produce 1 mole of Cr(OH)2.
Therefore, Therefore, 0.0121 mole of KOH will react with = (0.0121 x 1)/2 = 0.00605 mole of Cr(OH)2.
Finally, we shall convert 0.00605 mole of Cr(OH)2 to grams.
This is illustrated below:
Mole of Cr(OH)2 = 0.00605 mole
Molar mass of Cr(OH)2 = 52 + 2(16 + 1) = 52 + 2(17) = 86 g/mol
Mass of Cr(OH)2 =..?
Mole = mass /Molar mass
0.00605 = mass of Cr(OH)2/86
Cross multiply
Mass of Cr(OH)2 = 0.00605 x 86
Mass of Cr(OH)2 = 0.52 g
Therefore, 0.52 g of chromium(II) hydroxide, Cr(OH)2 was produced.
Given the following reaction and data, A + B → Products
Experiment A (M) B (M) Rate (M/s)
1 1.50 1.50 0.320
2 1.50 2.50 0.320
3 3.00 1.50 0.640
Required:
a. What is the rate law of the reaction?
b. What is the rate constant?
Answers
Answer:
a. Rate = k×[A]
b. k = 0.213s⁻¹
Explanation:
a. When you are studying the kinetics of a reaction such as:
A + B → Products.
General rate law must be like:
Rate = k×[A]ᵃ[B]ᵇ
You must make experiments change initial concentrations of A and B trying to find k, a and b parameters.
If you see experiments 1 and 3, concentration of A is doubled and the Rate of the reaction is doubled to. That means a = 1
Rate = k×[A]¹[B]ᵇ
In experiment 1 and to the concentration of B change from 1.50M to 2.50M but rate maintains the same. That is only possible if b = 0. (The kinetics of the reaction is indepent to [B]
Rate = k×[A][B]⁰
Rate = k×[A]b. Replacing with values of experiment 1 (You can do the same with experiment 3 obtaining the same) k is:
Rate = k×[A]
0.320M/s = k×[1.50M]
k = 0.213s⁻¹A star is observed from two positions of Earth in its orbit, in summer and winter. Which of these is the best method to calculate the approximate distance of the star from Earth? measure the parallax and use it in calculations measure the red shift of emitted light and use it in calculations use doppler effect to calculate the shift in light traveling from star to Earth in winter use doppler effect to calculate the shift in light traveling from star to Earth in summer
Answers
Answer:
measure the parallax and use it in calculations
Explanation:
got it right on test
There are many more stars at different distances from the earth. The distance to the stars calculated in light years and it is measured using parallax method.Thus option a is correct.
What is parallax method?Parallax method is used to measure the approximate distance of stars from earth. It uses the position of nearby star from two points opposite to earth and the small angular displacement observed from the remote stars are noted.
The orbit radius of earth and distance to the stars can be calculated from the parallactic angle p, that is one second of arc. Thus the distance is described in the units parsec.
The distance to the stars are usually calculated in light years. One parsec equals 3.26 light years. The nearest star to earth is named as proxima century having the distance parallax 0.76813'' which equals 4.24 light years. Thus, parallax is inversely proportional to the distance.
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A substance, W has a concentration of 0.02mol when its molar mass was found to be
74.0 gmol-1 . Another substance V contains 1.00x1023 atoms and has molar mass of
40.0gmol-1. Which of the two substances has the greater mass (in grams)? [L =
6.02x1023]
ii) A 250 cm3
solution contains 14.63g of sodium chloride (NaCl). Calculate the
concentration of the solution in moldm-3
[Na= 23, Cl = 35.5]
Answers
Answer:
Explanation:
mass of W in gram = mole x molecular weight
= .02 x 74 = 1.48 gm
mass of V in gram
first of all we shall calculate the no of moles of V
1 mole = 6.0 x 10²³ atoms
1 x 10²³ atoms = 1 / 6 moles
mass of V in grams
= 40 / 6
= 6.67 grams .
So V has greater mass .
ii )
molecular weight of sodium chloride
= 58.5 gm
14.63 gram of sodium chloride
= 14.63 / 58.5 = .25 moles
250 cm³ = 250 x 10⁻³ dm³
So 250 x 10⁻³ dm³ of solution contains .25 moles of salt
1 dm³ of solution will contain .25 / 250 x 10⁻³ mole
= 1 mole
so concentration of solution is 1 mole per dm³
Calculate the molar hydrogen ion concentration of each of the following biological solutions given the pH:
(a) gastric juice, pH= 1.80
(b) urine, pH 4.75 56.
Answers
Answer: A
Explanation: Calculate the molar hydrogen ion concentration of each of the following biological solutions given the pH, Urine pH= 4.90
A complexometric titration can also be used to determine the amount of calcium in milk. The calcium concentration in milk is typically 1,200 mg/L. How would you alter the procedure used in this experiment to determine milk calcium content
Answers
Answer:
d
Explanation:answer is d on edg 2020
