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2 years ago

What is a acid and how does it react with metals (chemical reaction)?

Chemistry

1 answer:

Alenkasestr [34]2 years ago

3 0

Explanation:

Acids are substances whose ph is lower than 7.Acids react with most metals to form a salt and hydrogen gas.

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The radioactive isotope of lead, Pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.

Marina86 [1]

Answer:

Therefore it will take 7.66 hours for 80% of the lead decay.

Explanation:

The differential equation for decay is

$\frac{dA}{dt}= kA$

$\Rightarrow \frac{dA}{A}=kdt$

Integrating both sides

ln A= kt+c₁

$\Rightarrow A= e^{kt+c_1}$

$\Rightarrow A=Ce^{kt}$ [ $e^{c_1}=C$ ]

The initial condition is A(0)= A₀,

$\therefore A_0=Ce^{0.k}$

$\Rightarrow C=A_0$

$\therefore A=A_0e^{kt}$ .........(1)

Given that the $Pb_{209}$ has half life of 3.3 hours.

For half life $A=\frac12 A_0$ putting this in equation (1)

$\frac12A_0=A_0e^{k\times3.3}$

$\Rightarrow ln(\frac12)= 3.3k$ [taking ln both sides, $ln \ e^a=a$ ]

$\Rightarrow k=\frac{ln \frac12}{3.3}$

⇒k= - 0.21

Now A₀= 1 gram, 80%=0.8

and A= (1-0.8)A₀ = (0.2×1) gram = 0.2 gram

Now putting the value of k,A and A₀in the equation (1)

$\therefore 0.2=1e^{(-0.21)\times t}$

$\Rightarrow e^{-0.21t}=0.2$

$\Rightarrow -0.21t= ln(0. 2)$

$\Rightarrow t= \frac{ln (0.2)}{-0.21}$

⇒ t≈7.66

Therefore it will take 7.66 hours for 80% of the lead decay.

3 0

3 years ago

A hydrocarbon is a compound that contains mostly carbon and hydrogen. Calculate the percent composition (by mass) of the followi

Katena32 [7]

C7H16, where C=12.01, and H=1.01, so the weight of the molecule would be 7(12.01)+16(1.01), or 100.23. The percentage of carbon would be found by ((7*12.01)/100.23)*100=83.88% Carbon
((16*1.01)/100.23)*100=16.12% Hydrogen

7 0

3 years ago

Which statement explains how the charges on objects determine the electric force between them?(1 point)

lubasha [3.4K]

Answer:

Objects with the same charge repel each other, and objects with opposite charges attract each other.

Explanation:

The Coulomb law states that opposite charges attract each other and like charges repel each other. That means two positive charges repel each other but a positive and a negative charge attract.

8 0

2 years ago

Read 2 more answers

What is one interaction between the geosphere and the cryosphere

nordsb [41]

The water cycle is one interaction between the geosphere and the cryosphere.

7 0

4 years ago

What is the density of lead (in g/cm^3 3 ) if a rectangular bar measuring 0.500 cm in height, 1.55 cm in width, and 25.00 cm in

Viktor [21]

Answer:

Density = 11.4 g/cm³

Explanation:

Given data:

Density of lead = ?

Height of lead bar = 0.500 cm

Width of lead bar = 1.55 cm

Length of lead bar = 25.00 cm

Mass of lead bar = 220.9 g

Solution:

Density = mass/ volume

Volume of bar = length × width × height

Volume of bar = 25.00 cm × 1.55 cm × 0.500 cm

Volume of bar = 19.4 cm³

Density of bar:

Density = 220.9 g/ 19.4 cm³

Density = 11.4 g/cm³

3 0

3 years ago