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bulgar [2K]
1 year ago
12

The ages of rocks that contain fossils can be determined using the isotope 87Rb. This isotope of rubidium undergoes beta

Chemistry
1 answer:
AVprozaik [17]1 year ago
7 0

Answer:

Age of rock = 722 million years old

Explanation:

Using the formula; <em>fraction remaining = 0.5ⁿ</em>

where n = number of half lives elapsed.

However, from the given values, fraction remaining = 1.000 - 0.0105

fraction remaining = 0.9895

Substituting in the formula to determine the number of half-lives:

0.9895 = 0.5ⁿ

log 0.9895 = n log 0.5  

-0.0045842 = -0.30103 n

number of half lives elapsed, n = 0.0152

Therefore age of rock = 0.0152 x 4.75 x 10¹⁰ years =  7.22 x10⁸ years

Age of rock = 722 million years old

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Write an equation to show how HC2O4− can act as a base with HS− acting as an acid.
Artyom0805 [142]

An acid donates H^{+} ion in aqueous solution. A base accepts H^{+} ion in aqueous solution.

The equation representing the acid base reaction of HC_{2}O_{4}^{-} and HS^{-}:

HC_{2}O_{4}^{-}(aq) + HS^{-}(aq) ----> H_{2}C_{2}O_{4}(aq)+S^{2-}(aq)

In the above reaction, as HC_{2}O_{4}^{-} acts as a base it is accepting the hydrogen ion from HS^{-}. Similarly, HS^{-} donates its hydrogen ion to HC_{2}O_{4}^{-} acting as an acid.

7 0
2 years ago
A gas that has a volume of 28 liters, a temperature of 45C, And an unknown pressure has its volume increased to 34 liters and it
patriot [66]

Answer:

P1 = 2.5ATM

Explanation:

V1 = 28L

T1 = 45°C = (45 + 273.15)K = 318.15K

V2 = 34L

T2 = 35°C = (35 + 273.15)K = 308.15K

P1 = ?

P2 = 2ATM

applying combined gas equation,

P1V1 / T1 = P2V2 / T2

P1*V1*T2 = P2*V2*T1

Solving for P1

P1 = P2*V2*T1 / V1*T2

P1 = (2.0 * 34 * 318.15) / (28 * 308.15)

P1 = 21634.2 / 8628.2

P1 = 2.5ATM

The initial pressure was 2.5ATM

3 0
1 year ago
The student decided to do another experiment with his leftover copper(II) sulfate (CuSO4) solution. He divided the solution up i
lakkis [162]

Answer:

CuSO4 + Fe -> FeSO4 + Cu

Explanation:

This reaction is a classic example of a redox reaction. I won't go in too deep, but the basic thing is that electrons from the Fe atom go to the Cu2+ ion. Therefore, Fe becomes an ion, and Cu - an electroneutral atom:

Fe + Cu2+ -> Fe2+ + Cu.

Silver is not a very reactive metal and it does not give up its electrons to Cu.

6 0
1 year ago
A sample of a compound of Cl and O reacts with an excess of H2 to give 0.233g of HCl and 0.403g of H2O. Determine the empirical
Vsevolod [243]

Answer:

Cl₂O₇

Explanation:

For the reaction:

ClₓOₙ + H₂ → HCl + H₂O

Moles of HCl and moles of H₂O are:

HCl: 0.233g HCl ₓ (1mol / 36.46g) = 6.39x10⁻³ mol HCl

H₂O: 0.403g H₂O ₓ (1mol / 18.02g) = 2.236x10⁻² mol H₂O

As you can see, moles of HCl are equivalent to moles of Cl in the compound and moles of H₂O are equivalent to moles of O in the compound, that means:

6.39x10⁻³ mol Cl

2.236x10⁻² mol O

Empirical formula is the simplest ratio of atoms presents in a molecule. If Cl is <em>1</em>, Oxygen will be:

2.236x10⁻² mol / 6.39x10⁻³ = <em>3.5</em>

As empirical formula must be given in natural numbers, the empirical formula is:

<em>Cl₂O₇</em>

<em></em>

4 0
2 years ago
Read 2 more answers
Calculate the heat of reaction, ΔH°rxn, for overall reaction for the production of methane, CH4.
Lesechka [4]

<u>Answer:</u> The enthalpy of the reaction for the production of CH_4 is coming out to be -74.9 kJ

<u>Explanation:</u>

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as \Delta H^o

The equation used to calculate enthalpy change is of a reaction is:  

\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f_{(product)}]-\sum [n\times \Delta H^o_f_{(reactant)}]

For the given chemical reaction:

C(s)+2H_2(g)\rightarrow CH_4(g)

The equation for the enthalpy change of the above reaction is:

\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(CH_4(g))})]-[(1\times \Delta H^o_f_{(C(s))})+(2\times \Delta H^o_f_{(H_2(g))})]

We are given:

\Delta H^o_f_{(C(s))}=0kJ/mol\\\Delta H^o_f_{(H_2)}=0kJ/mol\\\Delta H^o_f_{CH_4}=-74.9kJ/mol

Putting values in above equation, we get:

\Delta H^o_{rxn}=[(1\times (-74.9))]-[1\times 0)+(2\times 0)]\\\\\Delta H^o_{rxn}=-74.9kJ

Hence, the enthalpy of the reaction for the production of CH_4 is coming out to be -74.9 kJ

3 0
2 years ago
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