The sodium atom contains 11 electrons, 11 protons, and 12 neutrons. what is the mass number of sodium?

The pressure on 2.50 L of gas is changed from 4.5 atm to 2.2 atm. What is the new volume of gas?

swat32

Answer:

Explanation:

The new volume can be found by using the formula for Boyle's law which is

$P_1V_1 = P_2V_2$

Since we are finding the new volume

$V_2 = \frac{P_1V_1}{P_2} \\$

From the question we have

$V_2 = \frac{2.5 \times 4.5}{2.2} = \frac{11.25}{2.2} \\ = 5.1136666...$

We have the final answer as

Hope this helps you

8 0

3 years ago

I'm currently doing a Castle Learning part teacher and it's graded

kipiarov [429]

See the image below.

An excited electron is in a <em>high-energy state</em>.

When it drops to the lower-level ground state, it must get rid of this excess energy by <em>emitting it</em> as a quantum of light.

4 0

3 years ago

You are working in your laboratory and decide to do some cleaning. You find a test tube with some brown substance congealed at t

Anna [14]

Answer:

<em>The mystery substance is</em> <u>C. Bromine (Br) </u>

Explanation:

<em>Argon (Ar) </em>is a noble gas. Whose freezing point is -189 °C (very low), thus it cannot be the frozen substance. Also, it is not reactive, thus is would have not reacted with iron. Hence, argon is not the mystery substance.

<em>Scandium (Sc) </em>is a metal from group 3 of the periodic table, thus is will not react with iron. Thus, scandium is not the mystery substance.

Both <em>bromine</em> and <em>iodine</em> are halogens (group 17 of the periodic table).

The freezing point of bromine is −7.2 °C, and the freezing point of iodine is 113.7 °C. Thus, both could be solids (frozen) in the lab.

The reactivity of the halogens decrease from top to bottom inside the group. Bromine is above iodine. Then bromine is more reactive than iodine.

Bromine is reactive enough to react with iron. Iodine is not reactive enough to react with iron.

You can find in the internet that bromine vapour over hot iron reacts producing iron(III) bromide. Also, that bromine vapors are red-brown.

Therefore, <em>the mystery substance is bromine (Br).</em>

7 0

4 years ago

After 20 min, a reactant has decomposed to 85 % of its original concentration. Which order would the reaction need to be to allo

rjkz [21]

Answer : The value of rate constant is, $0.0949\text{ min}^{-1}$

Explanation :

First we have to calculate the rate constant, we use the formula :

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

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

where,

k = rate constant = ?

t = time passed by the sample = 20 min

a = let initial amount of the reactant = 100 g

a - x = amount left after decay process = 100 - 85 = 15 g

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

$k=\frac{2.303}{20}\log\frac{100}{15}$

$k=0.0949\text{ min}^{-1}$

Therefore, the value of rate constant is, $0.0949\text{ min}^{-1}$

7 0

3 years ago

What does expand mean in science

borishaifa [10]

Spread out, usually in every direction.

5 0

3 years ago

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