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3 years ago

When elements combine to form compounds does there properties change?

1 answer:

7 0

Yes, they do. The process described is a chemical reaction and it implies the change of nature of reactants and, of course, the change of its properties.

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Suppose the half-life is 9.0 s for a first order reaction and the reactant concentration is 0.0741 M 50.7 s after the reaction s

bazaltina [42]

<u>Answer:</u> The time taken by the reaction is 84.5 seconds

<u>Explanation:</u>

The equation used to calculate half life for first order kinetics:

$k=\frac{0.693}{t_{1/2}}$

where,

$t_{1/2}$ = half-life of the reaction = 9.0 s

k = rate constant = ?

Putting values in above equation, we get:

$k=\frac{0.693}{9}=0.077s^{-1}$

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}$ ......(1)

where,

k = rate constant = $0.077s^{-1}$

t = time taken for decay process = 50.7 sec

$[A_o]$ = initial amount of the reactant = ?

[A] = amount left after decay process = 0.0741 M

Putting values in equation 1, we get:

$0.077=\frac{2.303}{50.7}\log\frac{[A_o]}{0.0741}$

$[A_o]=3.67M$

Now, calculating the time taken by using equation 1:

$[A]=0.0055M$

$k=0.077s^{-1}$

$[A_o]=3.67M$

Putting values in equation 1, we get:

$0.077=\frac{2.303}{t}\log\frac{3.67}{0.0055}\\\\t=84.5s$

Hence, the time taken by the reaction is 84.5 seconds

6 0

3 years ago

The cell potential for an electrochemical cell with a Zn, Zn2 half-cell and an Al, Al3 half-cell is _____ V. Enter your answer t

kap26 [50]

Answer:

0.900 V

Explanation:

Oxidation half cell;

2Al(s) -----> 2Al^3+(aq) + 6e

Reduction half equation;

3Zn^2+(aq) + 6e ----> 3Zn(s)

E°anode = -1.66V

E°cathode= -0.76 V

E°cell= E°cathode - E°anode

E°cell= -0.76-(-1.66)

E°cell= 0.900 V

3 0

4 years ago

Why does a physical change occur when iodine is heated?

makkiz [27]

Answer:

Explanation:

when few crystals of iodine are added to test tube

the test tube gets heated and turns into a gas

which later soldifies to a liquid

I hope this helps

8 0

3 years ago

Why leaves often contain starch

Anastasy [175]

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7 0

4 years ago

Which group is least reactive of all the elements

Talja [164]

The group is called the noble gas i think

3 0

3 years ago