1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Alex_Xolod [135]
3 years ago
14

7. Use the concepts of relative abundance and relative weight to explain why carbon has an atomic mass of 12.011 amu when there

are three isotopes of carbon weighing 12 amu, 13 amu and 14 amu. Why is the atomic mass not 13?
Chemistry
1 answer:
Dvinal [7]3 years ago
5 0

The  uncertainties  of  the  delta  measurements  and  the  uncertainty  of  the  atomic  weight  derivedfrom  the  best  measurement  of  isotopic  abundances  constrain  the  number  of  significant  figures  in  theatomic-weight values of the upper and lower bounds. For carbon, the fifth digit after the decimal pointis uncertain because of the uncertainty value of 0.000 027. Therefore, the number of significant digitsin the atomic-weight value is reduced to four figures after the decimal point. The Commission may rec-ommend  additional  conservatism  and  reduce  the  number  of  significant  figures  further.  For  the  lowerbound of carbon, 12.009 635 is truncated to 12.0096. For an upper bound, the trailing digit is increasedto ensure the atomic-weight interval encompasses the atomic-weight values of all normal materials. Inthe case of carbon, the upper bound is adjusted from 12.011 532 to 12.0116 to express four digits afterthe decimal point. The lower and upper bounds are evaluated so that the number of significant digits ineach  is  identical.  If  a  value  ends  with  a  zero,  it  may  need  to  be  included  in  the  value  to  express  therequired number of digits. The following are examples of lower and upper atomic-weight bounds foroxygen that could be published by the Commission in its various tables.

---------------------------

Extracted from" Atomic weights of the elements 2009 (IUPAC Technical Report)"

You might be interested in
Calculate the Ka for the following acid. Determine if it is a strong or weak acid.
vladimir1956 [14]

Answer:

a) Ka= 7.1 × 10⁻⁴; This is a weak acid because the acid is not completely dissociated in solution.

Explanation:

Step 1: Write the dissociation reaction for nitrous acid

HNO₂(aq) ⇄ H⁺(aq) and NO₂⁻(aq)

Step 2: Calculate the acid dissociation constant

Ka = [H⁺] × [NO₂⁻] / [HNO₂]

Ka = 0.022 × 0.022 / 0.68

Ka = 7.1 × 10⁻⁴

Step 3: Determine the strength of the acid

Since Ka is very small, nitrous acid is a weak acid, not completely dissociated in solution.

4 0
3 years ago
Which of the following actions can a person take in order to best conserve fossil fuel resources?
iris [78.8K]
It’s c it has to be in certain
8 0
2 years ago
Read 2 more answers
What is the oxidation state of Hg in Hg2Cl2?​
Anna [14]

Answer:

+1

Explanation:

Electrochemistry. In oxidation–reduction (redox) reactions, electrons are transferred from one A redox reaction is balanced when the number of electrons lost by the reductant Hg(l)∣Hg2Cl2(s)∣Cl−(aq) ∥ Cd2+(aq)∣Cd(s).

As is evident from the Stock number, mercury has an oxidation state of +1. This makes sense, as chlorine usually has an oxidation state of -1.

5 0
3 years ago
Which two changes would make this reaction reactant-favored?
Vera_Pavlovna [14]

Two changes would make this reaction reactant-favored

C. Increasing the temperature

D. Reducing the pressure

<h3>Further explanation</h3>

Given

Reaction

2H₂ + O₂ ⇒ 2H₂0 + energy

Required

Two changes would make this reaction reactant-favored

Solution

The formation of H₂O is an exothermic reaction (releases heat)

If the system temperature is raised, then the equilibrium reaction will reduce the temperature by shifting the reaction in the direction that requires heat (endotherms). Conversely, if the temperature is lowered, then the equilibrium shifts to a reaction that releases heat (exothermic)  

While on the change in pressure, then the addition of pressure, the reaction will shift towards a smaller reaction coefficient  

in the above reaction: the number of coefficients on the left is 3 (2 + 1) while the right is 2

As the temperature rises, the equilibrium will shift towards the endothermic reaction, so the reaction shifts to the left towards H₂ + O₂( reactant-favored)

And reducing the pressure, then the reaction shifts to the left H₂ + O₂( reactant-favored)⇒the number of coefficients is greater

4 0
2 years ago
Select True or False from the pull down menus for the following statements.
Shkiper50 [21]

Answer:

First question: 1- False, 2- True, 3- False, 4 -Tue, 5- True.

Second question: 12.7 ºC

Explanation:

First question:

1- When a phase change for a pure substance is taking place under constant pressure, the temperature remains constant, and there's no sensitive heat flowing, but there's latent heat flow, which must be added to separate the molecules and to increase the kinetic energy.

2- When observed the heating and the cooling curve, at the phase change, there is no change in temperature, so it must be a horizontal line, which has a slope equal to 0.

3- Heat is the energy that is transferred by the substances or bodies because of a difference in temperature. The temperature is the measure of average kinetic energy in the molecules, so they are different.

4- As explained above, it's true, that's the definition of temperature.

5- Melting and freezing are the opposite processes and they occur at the same temperature. The difference is that for melting, the substance is absorbing heat, and for freezing it is losing heat, but the heat amount is the same for both process and is calculated by Q = ±m*L, where Q is the heat, m the mass, L the heat capacity, and the signal ± indicates if the substance is absorbing (+) or losing (-) heat.

Second question:

For the conservation of energy, the total amount of heat must be 0. The coin is losing heat, so it must be negative. The water is gaining heat, so it must be positive:

Qw - Qc = 0

Q = m*s*ΔT, where Q is the heat, m is the mass, s is the specif heat, and ΔT the temperature variation (final - initial). Qw is from water and Qc for the coin. The specif heat from the water is 4.184 J/gºC. At the thermal equilibrium, the final temperature must be equal for both.

mw*sw*ΔTw = mc*sc*ΔTc, if the coin is pure silver, sc = 0.233 J/gºC

27.0*4.184*(T - 15.5) = 15.5*0.233*(T - 100)

112.968*(T - 15.5) = 3.6115*(T - 100)

112.968T - 1751.004 = 3.6115T - 361.15

109.3565T = 1389.854

T = 1389.854/109.3565

T = 12.7ºC

So, the final water temperature would be 12.7ºC, which is impossible because it needs to increase. So the coin is not silver pure.

7 0
3 years ago
Other questions:
  • Jidkcusuwjxjfuieieidieiriririeir
    5·1 answer
  • Explain the scientific word meaning of random
    12·1 answer
  • Atoms join together to form compounds by gaining losing or sharing
    15·2 answers
  • as the difference in electronegativity between two atoms decreases, the tendency for the formation of covalent bonds
    9·1 answer
  • You heat two substances, A and B. Both substances change color. When cooled, substance A returns to its original color, but subs
    15·2 answers
  • Is iron likely to gain electrons, why?
    12·1 answer
  • Write a complete, balanced chemical equation where tin metal reacts with aqueous hydrochloric acid to produce tin(II) chloride a
    6·1 answer
  • Two answer multiple choice-- please help!
    5·1 answer
  • Help me with these problems please.
    13·1 answer
  • How many valence electrons does Oxygen have:<br> a) 3 <br> b) 5 <br> c) 13
    15·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!