An element has three isotopes: St-284 (34.60%), St-285 (21.20%), and St-288 (44.20%). What is its average atomic mass?

Answers

Answer 1

Answer: I believe that it’ll be 284.45

Explanation:

May have to double check but I’m pretty sure that’s correct sorry if it’s not


Related Questions

A chemist carefully measures the amount of heat needed to raise the temperature of a 341.0 mg
sample of a pure substance from 8.4 ℃
to 21.5 ℃. The experiment shows that 4.03 J of heat are needed.

- What can the chemist report for the specific heat capacity of the substance?

Answers

Answer:

The specific heat of substance is 0.90 j/g.°C.

Explanation:

Given data:

Mass of sample = 341.0 mg (341.0/1000 = 0.341 g)

Initial temperature = 8.4 °C

Final temperature = 21.5 °C

Heat needed = 4.03 J

Specific heat capacity of substance = ?

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = T2 - T1

ΔT = 21.5 °C - 8.4 °C

ΔT = 13.1 °C

4.03 J = 0.341 g × c ×13.1 °C

4.03 J = 4.4671 g.°C  × c

c = 4.03 J  /4.4671 g.°C

c= 0.90 j/g.°C

The specific heat of substance is 0.90 j/g.°C.

Which of the following is an example of a chemical name using prefixes?
O A. Carbon dioxide
O B. Magnesium sulfate
O C. Iron(ll) carbonate
O D. Potassium chloride

Answers

A.Carbon dioxide because I had the question on my test and I got it right

Answer:

A

Explanation:

CHOOSE ALL THE ANSWERS THAT APPLY. Which of the following equations are balanced?
O 2Fe + Cu(NO 3) 2 → 2Cu + Fe(NO 3) 2
O 2K + 2H 2O → H 2 + 2KOH
O Li + Cl 2 → LiCl
O 2H 2 + O 2 → 2H 2O
O 2S + 3O 2 → 2SO 3

Answers

Answer:

#2, 4, & 5

Explanation:

In number 1 there are unequal Cu's

In number 3 there are unequal Cl's

Answer:

B,D,E

Explanation:

Which is the best definition of nonpolar covalent bond?​

Answers

Answer:

It is one of the covalent bonds in which the electrons are shared equally; therefore, dipole moment exists between the atoms in a molecule and there is no charge separation between the atoms in a molecule.

Answer: A covalent bond in which the electrons are shared equally

Explanation:

A P E X

40. Which of these is an example of an
anhydrous compound?
A) H2O
C) CuSO4.5H2O
B) CaSO4
D) CaSO4 · 2H2O

Answers

Explanation:

CuSO4.5H2O and CaSO4.2H2O

Answer:

CaSO4 is an example of anhydrous compound

Reason:

Calcium Sulphate (CaSO4) does not contain water in its crystal structure, unlike other minerals.

You are given a sample of a Group II metal chloride, but the identity of the metal is unknown. Knowing that all Group II metal chloride compounds have the general formula, MCI2 and that the percentage of chlorine in the compound is 34.1%, what is the identity of the unknown substance?​

Answers

Answer:

The identity of unknown substance is Barium.

Explanation:

The given compound has a formula of MCl2. And the percentage of chlorine in this compound is said to be 34.1 %. But, we know that the mass of chlorine in this compound is, 35.5*2 = 71 g

Therefore, if we let x be the total mass of the compound, then:

34.1% of x = 71 g

(0.341)x = 71 g

x = 71 g/0.341

x = 208.2 g

Hence, the mass of other atom M, must be:

M = x - 71 g

M = 208.2 g - 71 g

M = 137.2 g

Now, we look into periodic table in group II. We find that the element is Barium with atomic mass of 137 g.

The identity of unknown substance is Barium.

Barium forms a metal chloride whose percentage of chlorine is 34.1 %. The unknown substance is barium chloride.

We have a Group II metal chloride with a general formula MCl₂. The molar mass of Cl⁻ is 35.45 g/mol. The mass of 2 moles of Cl⁻ is:

[tex]2 mol Cl^{-} \times \frac{35.45g Cl^{-} }{1mol Cl^{-} } = 70.90g Cl^{-}[/tex]

70.90 g represents 34.1% of 1 mole of MCl₂. The molar mass of MCl₂ is:

[tex]70.90gCl^{-} \times \frac{100gMgCl_2}{34.1gCl^{-} } = 208gMgCl_2[/tex]

208 g of MCl₂ contains 70.90 g of Cl⁻. The mass of M²⁺ in 1 mole of MCl₂ is:

[tex]mMCl_2 = mCl^{-} + mM^{2+} \\\\mM^{2+} = mMCl_2 - mCl^{-} = 208g-70.9 g = 137.1 g[/tex]

Barium has a molar mass of 137.3 g/mol, so M must be barium. The unknown substance is barium chloride.

Barium forms a metal chloride whose percentage of chlorine is 34.1 %. The unknown substance is barium chloride.

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Help me please I need help

Answers

Answer:

uijj uhh the yuk high uijj john

How many moles are there in 50.0 mL of a 3.20 M solution? 0.00250 mol 1.65 mol 0.00675 mol 0.160 mol

Answers

0.160 mols can be found in 50.0mL of 3.20M solution

Consider an isolated system (no heat, matter, work exchange with the environment) consisting of three internal compartments: A on the left, B in the center, and C on the right.Initially the central volume B is filled with an ideal gas at 298K andtheothertwo are empty. Consider the following two processes:a.The valve to the A side is opened, the gas expands freely into compartment A, and the system comesto equilibrium. Then, the valve to the C compartment is opened, and the system comes to equilibrium. b.Both valves are opened simultaneously, the gas expands freely into both compartments, and the system comes to its equilibrium. Which process produces more entropy

Answers

Answer:

Both processes produce equal entropy

Explanation:

Three compartments : A , B , C

A to the left, B in center, C on the right

compartment B is filled at 298 k  while A and C is empty

The process that produces more entropy is:  both processes and this is because the system is an isolated system with no heat matter and work exchange with the environment. and also entropy is independent of the path a process follows so either valve been open does not affect the entropy in the system because the change in the internal energy of an isolated system = 0

What is the pressure in kPa of 2 moles of chlorine gas at a temperature of 5 degrees C
and a volume of 8 dm3?

Answers

Answer:

[tex]P=5.8x10^2kPa[/tex]

Explanation:

Hello.

In this case, since chlorine gas is assumed to behave ideally, we can use the ideal gas equation in order to compute the required pressure:

[tex]PV=nRT[/tex]

In such a way, since the temperature must be in kelvins and the volume in liters for the universal gas constant:

[tex]T=5+273.15=278.15K\\\\V=8dm^3*\frac{1L}{1dm^3}=8L[/tex]

Thus, we first compute the pressure in atm:

[tex]P=\frac{nRT}{V}= \frac{2mol*0.082\frac{atm*L}{mol*K}*278.15K}{8L}\\\\P=5.7atm[/tex]

Thus, the pressure in kPa turns out:

[tex]P=5.7atm*\frac{101.325kPa}{1atm}\\\\P=5.8x10^2kPa[/tex]

Solve. C3H8(g) + 5O2(g) --> 3CO2(g) + 4H2O(g)

What is the Enthalpy of reaction?

What is the total Enthalpy of Reactants and Products? (Kj/Mol)

Is this a endothermic or exothermic reaction?

Answers

Answer: hope this helps!

Explanation:

Specific heat capacity of a substance is the amount of heat required to raise the temperature by one degree Celsius of one gram of a substance. Therefore,  the enthalpy of reaction is -2219.9KJ/mol and the reaction is exothermic reaction.

What is Enthalpy?

Enthalpy term is basically used in thermodynamics to show the overall energy that a matter have. Mathematically, Enthalpy is directly proportional to specific heat capacity of a substances.

Mathematically,

C[tex]_3[/tex]H[tex]_8[/tex](g) + 5O[tex]_2[/tex](g) [tex]\rightarrow[/tex]3CO[tex]_2[/tex](g) + 4H[tex]_2[/tex]O(g)

Mathematically, the formula for enthalpy of a reaction can be given as

ΔH for reaction= 3 ×ΔH of CO[tex]_2[/tex] + 4  ×ΔH of H[tex]_2[/tex]O- ΔH of  C[tex]_3[/tex]H[tex]_8[/tex]+ 5 ×ΔH of O[tex]_2[/tex]

                        =  3 ×393.5KJ/mol+ 4  ×285.8- 103.8+ 5 ×0

                        =-2219.9KJ/mol

The  enthalpy of reaction is -2219.9KJ/mol. since the value of enthalpy has negative sign, the reaction is exothermic reaction.

Therefore,  the enthalpy of reaction is -2219.9KJ/mol and the reaction is exothermic reaction.

To know more about enthalpy, here:

https://brainly.com/question/24170335

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pls answer and i will mark u brainliest
question:- A precious metal used in jewelry and found in a pure form in nature is:
options are :-
a. Silver
b. platinum
c. Zinc
d. copper

Answers

silver is a precious metal found in nature
Platinum should be the right answer

2 What do you notice about the location of the elements in each family?​

Answers

Explanation:

They are indeed placed from the far left hand side of the periodic table in almost the same column. If you step around the table between left to right, the movement of electrons rises by one. When you progress down the line, the number of power increases by the one.

What is the chemical name for LiC2H3O2 or C2H3O2Li

Answers

Answer:

AWAWDWDAD

Explanation:

what are the coefficients for the reaction _Cl2O5+_H2O>_HCIO3 once it is balanced

Answers

Answer:

1.9472857e+56

Explanation: Ask Google

Which has the lowest pH?
water
baking soda
bleach vinegar

Answers

Answer:

c. baking soda

Explanation:

A solution contains 90 mL of methanol, 18 mL of propanol, and 2 mL of diethyl ether. Which is the solvent in this solution?

Answers

Answer:

Methanol

Explanation:

How many electrons are in the 4p orbital does Br possesses?

Answers

Answer:

5 electron

It contains 6 electrons in 2p orbital, 6 electrons in 3p orbital and 5 electron in 4p orbital.

The skeletal structure in line-angle (line-bond) mode of 2,3,3,5-tetramethylhexane is shown. Identify the number of hydrogen atoms bound to each carbon atom in the structure.

Answers

Answer:

There are 22 hydrogen in 2,3,3,5-tetramethylhexane (C10H22)

From the left to the right of the skeletal structure:

1st Main Carbon = 3 hydrogen

2nd Main Carbon = 1 hydrogen

1st Branch Carbon = 3 hydrogen

3rd Main Carbon = 2 hydrogen

2nd Branch Carbon = 3 hydrogen

3rd Branch Carbon = 3 hydrogen

4th Main Carbon = 0 hydrogen

4th Branch Carbon = 3 hydrogen

5th Main Carbon = 1 hydrogen

6th Main Carbon = 3 hydrogen

Total = 22 hydrogen

Explanation:

This is the skeletal formula for 2,3,3,5-tetramethylhexane - the 2D chemical structure. It is an organic compound. The carbon atoms in the structure are known as the carbon backbone. The hydrogen atoms are linked to the carbon backbone. This provides each carbon atom with four bonds.

P, F, Cl, Si, C, O, Mg
Which of the elements above is the least electronegative?

Answers

Answer:

Mg

Explanation:

Electronegativity increase to the right and top of the periodic table. So the element that is the most toward the left and bottom is the least electronegative.

Aspirin synthesis involves the addition of an acetyl group to salicylic acid in a condensation reaction with an alcohol. The acetyl group could be added with a carboxylic acid but the preferred procedure is to use the acid anhydride. Why is preferable to use an acid anhydride for ester formation with an alcohol rather than a carboxylic acid? Select one: Carboxylic acids react with water in an undesired side reaction. Acid anhydrides are generally easier and safer to handle than carboxylic acids. Carboxylic acids change the pH of the solution too much for the reaction to proceed. Acid anhydrides are less stable than esters so the equilibrium favors the ester product.

Answers

Answer:

The correct appropriate will be Option 1 (Acid anhydrides are less stable than esters so the equilibrium favors the ester product.)

Explanation:

Acid anhydride, instead of just a carboxyl group, is typically favored for esterification. The predominant theory would be that Anhydride acid is somewhat more volatile than acid. This is favored equilibrium changes more toward the right of the whole ester structure. Extremely responsive than carboxylic acid become acid anhydride as well as acyl chloride. Thus, for esterification, individuals were most favored.

The other options offered are not relevant to something like the scenario presented. So, the solution here is just the right one.

which is the part of an experiment that serves as the point of comparison for the results

Answers

Answer:

the observation point.

Explanation:

after the experiment, you observe the data and comparing and write out formulas for the given data.

What does Prokaryotic have that other cells does not

Answers

Answer:

Prokaryotes are unicellular organisms that lack membrane-bound structures, the most noteworthy of which is the nucleus. ... While prokaryotic cells do not have membrane-bound structures, they do have distinct cellular regions. In prokaryotic cells, DNA bundles together in a region called the nucleoid.

Which one of the following statements about the β-sheet is FALSE? The β-sheet is a type of regular secondary structure. β-sheets can be parallel or antiparallel. The β-sheet contains hydrogen bonds between the carbonyl oxygen of one residue and an amide hydrogen of a residue on an adjacent strand. The side chains in a β-sheet alternate between the two sides of the sheet. The β-sheet is a type of secondary structure that fulfills the hydrogen bonding requirements of amino acid side chains. g

Answers

Answer:

The correct answer is "The β-sheet is a type of secondary structure that fulfills the hydrogen bonding requirements of amino acid side chains".

Explanation:

Hydrogen bonding are among the most common chemical bonds that occur between amino acids, where one atom of an amino acid acts as an hydrogen donor and the other acts as hydrogen acceptor. It is not true that β-sheet fulfills the hydrogen bonding requirements of amino acid side chains. β-strands are directional and form hydrogen bonds in antiparallel, parallel, or mixed arrangements. In the parallel form adjacent amino acids do not form hydrogen bonds, but they bond with the residues that flank the other.

The statement related to β-sheet that is considered to be false is that it should be the type of the secondary structure.

What is Hydrogen bonding?

It is the bonding that should be arise mainly with the chemical bonds that lies between the amino acids where one atom should be acted as the donor of hydrogen and the other should be like an acceptor of hydrogen. Also, β-strands should be considered as directional and create the hydrogen bonds in the anti-parallel or mixed arrangements.

Learn more about bonds here: https://brainly.com/question/17957192

Which evidence did Alfred Wegener use as evidence for the Continental Drift Theory?
Group of answer choices

A)South America and Africa fit like a puzzle.

B)Matching fossils on different continents

C)Similar rock types on the East coast of North America and Western Europe

D)All of the above

Answers

For this problem
D all of the above

how can i separate water salt starch​

Answers

Decantation
Centrifugation
Filtration
Evaporation

Answer:

By Boiling Them soo water can evaporate and separates from salt.

Fluorine has seven electrons in its outermost shell. It will most likely try to join with an atom with _____.
seven electrons in its outermost shell
two electrons in its outermost shell
one electron in its outermost shell
eight electrons in its first shell

Answers

Answer:

Its either with itself to become fluoride Fl2 or with an alkali metal (elements in group 1) to achieve a stable electronic configuration or octet structure

Explanation:

help me please i don’t understand the problem

Answers

Answer:

Atoms are neither created or destroyed.

Explanation:

The end result of a chemical change does not create or destroy any atoms. Matter cannot be created or destroyed, meaning the same amount of atoms exist before and after the change.

A. Atoms are neither created nor destroyed

Which of the following planets has ammonia clouds in its atmosphere?

Jupiter
Mars
Mercury
Venus

Answers

Answer:

Jupiter and Saturn has ammonia clouds in its atmosphere since the molecules of ammonia gas that are present in their atmospheres condense to form clouds. However, these ammonia clouds are more visible in Jupiter than in Saturn because of their lower altitude in Saturn.

Answer:

A

Explanation:

i took the exam

(PLEASE HURRY) Which of the following statements is an example of quantitative data? A. There are ten butterflies. B. The butterflies are red with yellow spots. C. The butterflies are eating nectar from the flower. D. The butterflies are flying.

Answers

answer: a
explaination: it said it needs to be 20 characters but the answer is a
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