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3 years ago

If the half-life of a radioactive substance is 2 seconds, how much of a 100-gram sample would be left after 8 seconds?

Chemistry

1 answer:

Elan Coil [88]3 years ago

4 0

M₀=100 g
T=2 s
t=8s

m=m₀/{2^(t/T)}

m=100/{2^(8/2)}=100/2⁴=6.25 g

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2 years ago

A/1 * B/C = D

grigory [225]

Answer : 4.8 florins can you exchange for your 4 guilders.

Solution : Given,

The current exchange rate for every 2.4 florins is 2.0 guilders

As per question,

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The exchange rate is 1 guilders for every $\frac{2.4}{2.0}$ florins

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2 years ago

The half life for the first order conversion of A to B is 56.6 hours. How long does it take for the concentration of A to decrea

sveta [45]

Answer:

It will take 188.06 hours for the concentration of A to decrease 10.0% of its original concentration.

Explanation:

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Initial concentration of the reactant = x

Final concentration of reactant = 10% of x = 0.1 x

Time taken by the sample, t = ?

Formula used :

$A=A_o\times e^{-\lambda t}\\\\\lambda =\frac{0.693}{t_{\frac{1}{2}}}$

where,

$A_o$ = initial concentration of reactant

A = concentration of reactant left after the time, (t)

$t_{\frac{1}{2}}$ = half life of the first order conversion = 56.6 hour

$\lambda$ = rate constant

$A=A_o\times e^{-(\frac{0.693}{t_{1/2}})\times t}$

Now put all the given values in this formula, we get

$0.1x=x\times e^{-(\frac{0.693}{56.6 hour})\times t}$

t = 188.06 hour

It will take 188.06 hours for the concentration of A to decrease 10.0% of its original concentration.

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3 years ago

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3 years ago

What mass of water (in grams) is produced by the reaction of 23.0 g of SiO2?

nikitadnepr [17]

The mass of water produced by the reaction of the 23 g of $SiO_2$ is 13.8 g.

The given chemical reaction;

$4Hf (g) \ + \ SiO_2 (s) \ --> \ SiF_4(g) \ + \ 2H_2O(l)$

In the given compound above, we can deduce the following;

molecular mass of $SiO_2$ = 28 + (2 x 16) = 60 g
molecular mass of $2H_2O$ = 2(18) = 36 g

60 g of $SiO_2$ --------- 36 g of water

23 g of $SiO_2$ ------------- ? of water

$mass \ of \ water = \frac{23 \times 36}{60} = 13.8 \ g \ of \ water$

Thus, the mass of water produced by the reaction of the 23 g of $SiO_2$ is 13.8 g.

<em>"Your question is not complete, it seems to be missing the following information";</em>

In the reaction of the given compound, $4Hf (g) \ + \ SiO_2 (s) \ --> \ SiF_4(g) \ + \ 2H_2O(l)$ , what mass of water (in grams) is produced by the reaction of 23.0 g of SiO2?

Learn more here:brainly.com/question/13644576

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2 years ago