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
Molodets [167]
3 years ago
11

What isotope has 18 protons and 22 neutrons?

Chemistry
1 answer:
Nesterboy [21]3 years ago
6 0

Answer:

Argon.

Explanation:

Argon is the element having 18 protons and 22 neutrons present in its nucleus. so its atomic number is 18 and mass number is 40 if we added both number of protons and neurons. Argon belongs to noble family due to completion of outermost shell and non reactive nature. It is the third most abundant gas about 0.934% present on the earth after nitrogen and oxygen.

You might be interested in
How do limiting factors most affect population size?
damaskus [11]

Answer:

restrict population growth ( second choice).

8 0
3 years ago
Do you expect potassium iodide to be soluble in cyclohexane
Allushta [10]
Answer is: no, <span>potassium iodide has low solubility in cyclohexane.
</span>Potassium iodide (KI) is ionic compound, salt, that dissolve good in polar solvents (for example water), but it is very low soluble in non-polar solvents (in this example cyclohexane C₆H₁₂).
<span>Cyclohexane has zero net polarity, because it is a symmetric molecule, with sp2 hybridization of carbon.</span>
8 0
4 years ago
Read 2 more answers
The density of lava is 3.1 g/cm². It has a volume of 2700 cm3. How much does this block of lava weigh?
konstantin123 [22]

Answer:

Mass of lava is 8370 g.

Explanation:

Density:

Density is equal to the mass of substance divided by its volume.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Symbol:

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Given data:

density of lava = 3.1 g/cm³

volume= 2700 cm³

mass= ?

Solution:

d = m/v

m = d×v

m = 3.1 g/cm³×2700 cm³

m = 8370 g

4 0
3 years ago
Calculate Delta H in KJ for the following reactions using heats of formation:
lozanna [386]

Answer:

<h3>(a)</h3>

\Delta H\textdegree = -2856.8\;\text{kJ} per mole reaction.

<h3>(b)</h3>

\Delta H\textdegree = -22.3\;\text{kJ} per mole reaction.

Explanation:

What is the standard enthalpy of formation \Delta H_f\textdegree{} of a substance? \Delta H_f\textdegree{} the enthalpy change when one mole of the substance is formed from the most stable allotrope of its elements under standard conditions.

Naturally, \Delta H_f\textdegree{} = 0 for the most stable allotrope of each element under standard conditions. For example, oxygen \text{O}_2 (not ozone \text{O}_3) is the most stable allotrope of oxygen. Also, under STP \text{O}_2  is a gas. Forming \text{O}_2\;(g) from itself does not involve any chemical or physical change. As a result, \Delta H_f\textdegree{} = 0 for \text{O}_2\;(g).

Look up standard enthalpy of formation \Delta H_f\textdegree{} data for the rest of the species. In case one or more values are not available from your school, here are the published ones. Note the state symbols of the compounds (water/steam \text{H}_2\text{O} in particular) and the sign of the enthalpy changes.

  • \text{C}_2\text{H}_6\;(g): -84.0\;\text{kJ}\cdot\text{mol}^{-1};
  • \text{CO}_2\;(g): -393.5\;\text{kJ}\cdot\text{mol}^{-1};
  • \text{H}_2\text{O}\;{\bf (g)}: -241.8\;\text{kJ}\cdot\text{mol}^{-1};
  • \text{PbO}\;(s): -217.9\;\text{kJ}\cdot\text{mol}^{-1};
  • \text{PbO}_2\;(s): -276.6\;\text{kJ}\cdot\text{mol}^{-1};
  • \text{Pb}_3\text{O}_4\;(s): -734.7\;\text{kJ}\cdot\text{mol}^{-1}

How to calculate the enthalpy change of a reaction \Delta H_\text{rxn} (or simply \Delta H from enthalpies of formation?

  • Multiply the enthalpy of formation of each product by its coefficient in the equation.
  • Find the sum of these values. Label the sum \Sigma (n\cdot \Delta_f(\text{Reactants})) to show that this value takes the coefficients into account.
  • Multiply the enthalpy of formation of each reactant by its coefficient in the equation.
  • Find the sum of these values. Label the sum \Sigma (n\cdot \Delta_f(\text{Products})) to show that this value takes the coefficient into account.
  • Change = Final - Initial. So is the case with enthalpy changes. \Delta H_\text{rxn} = \Sigma (n\cdot \Delta_f(\textbf{Products})) - \Sigma (n\cdot \Delta_f(\textbf{Reactants})).

For the first reaction:

  • \Sigma (n\cdot \Delta_f(\text{Reactants})) = 4\times (-393.5) + 6\times (-241.8) = -3024.8\;\text{kJ}\cdot\text{mol}^{-1};
  • \Sigma (n\cdot \Delta_f(\text{Products})) = 2\times (-84.0) + 7\times 0 = -168.0\;\text{kJ}\cdot\text{mol}^{-1};
  • \begin{aligned}\Delta H_\text{rxn} &= \Sigma (n\cdot \Delta_f(\textbf{Products})) - \Sigma (n\cdot \Delta_f(\textbf{Reactants}))\\ &= (-3024.8\;\text{kJ}\cdot\text{mol}^{-1}) - (-168.0\;\text{kJ}\cdot\text{mol}^{-1})\\ &= -2856.8\;\text{kJ}\cdot\text{mol}^{-1} \end{aligned}.

Try these steps for the second reaction:

\Delta H_\text{rxn} = -22.3\;\text{kJ}\cdot\text{mol}^{-1}.

6 0
4 years ago
20 g of water. specific heat of water is 4.18 J/x°C. temperature changes from
pashok25 [27]

Answer:

B or the second one

Explanation:

8 0
3 years ago
Read 2 more answers
Other questions:
  • Choose the best description of what is wrong with the following electron configuration for an electrically neutral atom of Chlor
    5·1 answer
  • Using the relation dS = (δQ/T)int rev for the definition of entropy, calculate the change in the specific entropy of R-134a as i
    5·1 answer
  • Why do an atoms electrons revolve around its proton instead of drifting away?
    10·1 answer
  • An unknown substance turns methyl orange solution red. This shows that the substance is a base. is water. is an acid. is an alka
    11·1 answer
  • What property of hydrocarbon molecules correlates to the viscosity of a particular fraction when it is cooled to room temperatur
    15·2 answers
  • Which of the following are analogous features? A. dolphin flippers and squirrel arms B. elephant trunks and pig snouts C. rabbit
    11·1 answer
  • Explain how illustration on the left creates a higher pressure??
    11·1 answer
  • Which of the following are good conductors
    11·2 answers
  • Explain why the addition of a catalyst can make a reaction occur that doesn't normally occur at room temperature even when AG&lt
    7·1 answer
  • Lack of sleep significantly affects learning in middle schoolers. What is the independent variable?
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!