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ryzh [129]
3 years ago
12

When does the composition of a substance does not change?

Chemistry
1 answer:
blagie [28]3 years ago
4 0
I think when it does not react with anything I think
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Calculate the energy E (in MeV) released in the following nuclear fission reaction: 242 Am + X → 90 Sr + 149 La + 4 n Start by c
KonstantinChe [14]

Answer:

177.993 MeV

Explanation:

Nuclear fission refers to a process where a nucleus is broken into smaller ones.

m(Am) = 242.0595490 u, m(Sr) = 89.9077387 u, m(La) = 148.934733 u and m(n) = 1.008665 u. To find the mass of X, we sum up the masses on both side and subtract them according to the equation given

242 + X = 90 +149 + 4

X = 243 - 242 = 1

so X is a neutron

next we calculate the Δm ( change in mass)

Δm = mass reactant - mass of product

(242.0595490 + 1.008665 ) - ( 89.9077387 + 148.934733  + 4 (1.008665))

= 243.068214 - 242.8771317 = 0.1910823 u

using the formula

E = (Δm) c² = 0.1910823 u × c² × \frac{931.5MeV}{c^2}× \frac{1}{u} = 177.993 MeV

8 0
4 years ago
How many phases does a solution have?explain
Vikki [24]
Did you perhaps mean the phase of matter? If so, then a solution has only one phase of matter: liquid. It is always almost always liquid because solutions are made up of a solvent and a solute and a solvent is always a liquid. Though, some may come in an emulsion form, but still it can be considered as liquid
4 0
4 years ago
A gas has a mass of 3.82 g and occupies a volume of 0.854 L. The temperature in the laboratory is 302 K, and the air pressure is
Rzqust [24]

The molar mass of the gas that has a mass of 3.82 g and occupies a volume of 0.854 L is 106.66g/mol.

<h3>How to calculate molar mass?</h3>

The molar mass of a substance can be calculated by dividing the mass of the substance by its number of moles.

However, the number of moles of the gas in this question needs to be calculated first using the ideal gas law equation:

PV = nRT

Where;

  • P = pressure
  • V = volume
  • n = number of moles
  • T = temperature
  • R = gas law constant

1.04 × 0.854 = n × 0.0821 × 302

0.888 = 24.79n

n = 0.888/24.79

n = 0.036mol

Molar mass of gas = 3.82g/0.036mol

Molar mass = 106.66g/mol

Therefore, the molar mass of the gas that has a mass of 3.82 g and occupies a volume of 0.854 L is 106.66g/mol.

Learn more about molar mass at: brainly.com/question/12127540

3 0
2 years ago
7. Diethyl ether burns in air according to the following equation. C4H10O(l) + 6O2 (g) → 4CO2 (g) + 5H2O(l) If 7.15 L of CO2 is
iren [92.7K]

From the stoichiometry of the combustion reaction, we can see that 7.4 L of oxygen is consumed.

<h3>What is combustion?</h3>

Combustion is a reaction in which a substance is burnt in oxygen. The equation of the reaction is; C4H10O(l) + 6O2 (g) → 4CO2 (g) + 5H2O(l)

We can obtain the number of moles of CO2 from;

PV = nRT

n = 1.02 atm * 7.15 L/0.082 atm LK-1mol-1 * (125 + 273) K

n = 7.29 /32.6

n = 0.22 moles

If 6 moles of oxygen produces 4 moles of CO2

x moles of oxygen produces 0.22 moles of CO2

x = 0.33  moles

1 mole of oxygen occupies 22.4 L

0.33 moles of oxygen occupies 0.33 moles *  22.4 L/ 1 mole

= 7.4 L of oxygen

Learn more about stoichiometry: brainly.com/question/13110055

#SPJ1

6 0
3 years ago
The decomposition of hydrogen peroxide, H2O2, has been used to provide thrust in the control jets of various space vehicles. Usi
lesantik [10]

Answer:

\Delta H^0 _{reaction} = - 54.04 \ kJ/mol

Explanation:

The given equation for the chemical reaction can be expressed as;

2H_2O_{(l)}  \to 2H_2O_{(g)} +  O_{2(g)}

Using Hess Law to determine how much heat is produced by the decomposition of exactly 1 mole of H2O2 under standard conditions; we have the expression showing the Hess Law as follows:

\Delta H^0 _{reaction} = \sum n* \Delta H^0 _{products} -  \sum n* \Delta H^0 _{reactants}

At standard conditions;

the molar enthalpies of the given equation are as follows:

\Delta H_2O_{(g)} =-241.82\ kJ/mol

\Delta H_  O_{2(g)} = 0 \ kJ/mol

\Delta H _{H_2O_{(l)}}= -187.78  \ kJ/mol

Replacing them into above formula; we have:

\Delta H^0 _{reaction} = (2*(-241.82\ kJ/mol) + 0 \ kJ/mol + (2 *(-187.78 \ kJ/mol))

\Delta H^0 _{reaction} =-108.08 \ kJ/mol

The above is the amount of heat of formation for two moles of hydrogen peroxide; thus for 1 mole hydrogen peroxide ; we have :

\Delta H^0 _{reaction} = \dfrac{-108.08 \ kJ/mol}{2}

\Delta H^0 _{reaction} = - 54.04 \ kJ/mol

Hence; the heat produced after the decomposition of 1 mole of hydrogen peroxide is -54.04 kJ/mol

6 0
4 years ago
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