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3 years ago

If the chemical properties of a substance remain unchanged and the appearance or shape of an substance changes it is called a

Chemistry

2 answers:

Akimi4 [234]3 years ago

5 0

Answer:

Explanation:

physical change is the answer I hope

Morgarella [4.7K]3 years ago

3 0

Answer:

Explanation:

it is A because i am really smart

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What element is this? How do you know?

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3 years ago

Read 2 more answers

N2O5 decomposes to form NO2 and O2 with first-order kinetics. The initial concentration of N2O5 is 3.0 M and the reaction runs f

kow [346]

Answer : The final concentration of $N_2O_5$ is, 2.9 M

Explanation :

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $5.89\times 10^{-3}\text{ min}^{-1}$

t = time passed by the sample = 3.5 min

a = initial concentration of the reactant = 3.0 M

a - x = concentration left after decay process = ?

Now put all the given values in above equation, we get

$3.5=\frac{2.303}{5.89\times 10^{-3}}\log\frac{3.0}{a-x}$

$a-x=2.9M$

Thus, the final concentration of $N_2O_5$ is, 2.9 M

3 0

3 years ago

Which solution below has the highest concentration of hydroxide ions?a. pH= 3.21b. pH= 7.00c. pH= 7.93d. pH= 12.59e. pH= 9.82

Sloan [31]

Answer:

The solution that has the highest concentration of hydroxide ions is d. pH = 12.59.

Explanation:

You can solve this question using just some chemical facts:

pH is a measure of acidity or alkalinity: the higher the pH the lower the acidity and the higher the alkalinity.
The higher the concentration of hydroxide ions the lower the acidity or the higher the alkalinity of the solution, this is the higher the pH.

Hence, since you are asked to state the solution with the highest concentration of hydroxide ions, you just pick the highest pH. This is the option d, pH = 12.59.

These mathematical relations are used to find the exact concentrations of hydroxide ions:

pH + pOH = 14 ⇒ pOH = 14 - pH

pOH = - log [OH⁻] ⇒ $[OH^-]=10^{-pOH}$

Then, you can follow these calculations:

Solution pH pOH [OH⁻]

a. 3.21 14 - 3.21 = 10.79 antilogarithm of 10.79 = 1.6 × 10⁻¹¹

b. 7.00 14 - 7.00 = 7.00 antilogarithm of 7.00 = 10⁻⁷

c. 7.93 14 - 7.93 = 6.07 antilogarithm of 6.07 = 8.5 × 10⁻⁷

d. 12.59 14 - 12.59 = 1.41 antilogarithm of 1.41 = 0.039

e. 9.82 14 - 9.82 = 4.18 antilogarithm of 4.18 = 6.6 × 10⁻⁵

From which you see that the highest concentration of hydroxide ions is for pH = 12.59.

5 0

3 years ago