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Taya2010 [7]
3 years ago
7

After 4 half-lives 10 grams of uranium remains. How much uranium did you start with?

Chemistry
1 answer:
Free_Kalibri [48]3 years ago
4 0

Answer:

i think 40 grams

Explanation:

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Aluminum chloride can be formed from its elements:
saul85 [17]

<u>Answer:</u> The \Deltas H^o_{formation} for the reaction is -1406.8 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The chemical reaction for the formation reaction of AlCl_3 is:

2Al(s)+3Cl_2(g)\rightarrow 2AlCl_3 (s)    \Delta H^o_{formation}=?

The intermediate balanced chemical reaction are:

(1) HCl(g)\rightarrow HCl(aq.)    \Delta H_1=-74.8kJ    ( ×  6)

(2) H_2(g)+Cl_2(g)\rightarrow 2HCl(g)    \Delta H_2=-185kJ     ( ×  3)

(3) AlCl_3(aq.)\rightarrow AlCl_3(s)    \Delta H_3=+323kJ     ( ×  2)

(4) 2Al(s)+6HCl(aq.)\rightarrow 2AlCl_3(aq.)+3H_2(g)    \Delta H_4=-1049kJ

The expression for enthalpy of formation of AlCl_3 is,

\Delta H^o_{formation}=[6\times \Delta H_1]+[3\times \Delta H_2]+[2\times \Delta H_3]+[1\times \Delta H_4]

Putting values in above equation, we get:

\Delta H^o_{formation}=[(-74.8\times 6)+(-185\times 3)+(323\times 2)+(-1049\times 1)]=-1406.8kJ

Hence, the \Deltas H^o_{formation} for the reaction is -1406.8 kJ.

6 0
2 years ago
What is a decay series?
denpristay [2]

Answer:

D

Explanation:

because in a decay series a daughter nuclei may be stable or decay itself. that starts a decay series

5 0
3 years ago
Read 2 more answers
Question:
Nikolay [14]

Answer:

Chemistry teacher

Pharmaceuticals

Biochem/biotech

Materials science

Food chemist

Explanation:

Chemistry teaching

Teaching jobs in chemistry can range from teaching in public middle and high schools (bachelor’s degree required) to junior or community college (master’s degree required) to the university level (doctorate required). At the university level, you get to do research along with your teaching responsibilities.

Pharmaceutical/chemical sales

If you like chemistry but don’t enjoy being in the lab, then sales may be the job for you. Somebody has to sell all those chemicals and medicines, and buyers like to deal with somebody who knows their science.

Biochem/biotech

Biochemists and biotechnologists work in research developing new genetic tests, work in the genetic engineering (cloning) area, and are involved in the development of new drugs.

Materials science

Material scientists study the composition and structure of various materials with the goal of developing new products or improving existing ones.

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please give thanks, hit the heart button! :)

5 0
3 years ago
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What is the ph of a solution of 0.400 m k2hpo4, potassium hydrogen phosphate?
dusya [7]
When we can get Pka for K2HPO4 =6.86 so we can determine the Ka :

when Pka = - ㏒ Ka

          6.86 = -㏒ Ka 

∴Ka = 1.38 x 10^-7

by using ICE table:

               H2PO4- →  H+  + HPO4
initial      0.4 m            0         0

change     -X                +X       +X

Equ       (0.4-X)               X          X

when Ka = [H+][HPO4] / [H2PO4-]

by substitution:

1.38 X 10^-7 = X^2 / (0.4-X)   by solving for X

∴X = 2.3x 10^-4 

∴[H+] = X = 2.3 x 10^-4

∴PH = -㏒[H+]

        = -㏒ (2.3 x 10^-4)
 ∴PH  =  3.6

3 0
3 years ago
Last week you reacted magnesium with a hydrochloric acid aqueous solution and hydrogen gas was produced. Let's say that you coll
miv72 [106K]

Answer:

69.8 kilo Pasacl is the pressure of the hydrogen gas.

Explanation:

Mg+2HCl\rightarrow MgCl_2+H_2

Pressure at which hydrogen gas collected = p = 101.2 kilo Pascals

Vapor pressure water = p^o = 31.4 kilo Pascals

The pressure of hydrogen gas = P

The pressure at which gas was collected was sum of vapor pressure of water and hydrogen gas.

p=P+p^o

P =p-p^o=101.2 kPa-31.4 kPa=69.8 kPa

69.8 kilo Pasacl is the pressure of the hydrogen gas.

3 0
3 years ago
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