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3 years ago

The atomic number is always equal to the atomic mass true false

Chemistry

1 answer:

kifflom [539]3 years ago

7 0

Answer:

<h3>A neutral (no charge) particle found in the nucleus of an atom. ... The atomic number of an atom is equal to the number of protons or neutrons? false. The atomic number is always equal to the atomic mass.</h3>

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How many different sets of equivalent protons are there for para-xylene (1,4-dimethylbenzene)? only 1 two three four?

ELEN [110]

Answer:

Two

Step-by-step explanation:

There are two ways to determine the number sets of equivalent protons in a compound.

(a) By substitution

Replace each H with a different group and see if you get a different compound

For example, the six CH₃ H atoms are an equivalent set, because, if I replace any one of them, I will always get the same compound: 1-chloromethyl-4-methylbenzene (Fig. 1).

Similarly, the four aromatic H atoms are an equivalent set. If I replace any one of them, I will always get the same compound: 2-chloro-1,4-dimethylbenzene (Fig. 2).

Thus, there are two sets of equivalent protons in p-xylene.

(b) By symmetry

Two atoms are equivalent if one can be converted into the other by a symmetry operation on the molecule.

The methyl hydrogens can be interconverted by a combination of reflections about the AB and CD mirror planes and by rotations about the C-C bonds to the ring (Fig. 3).

Similarly, the four aromatic H atoms can be interconverted by a combination of reflections about the AB and CD mirror planes.

Again, we find two sets of equivalent protons.

7 0

3 years ago

How would you measure the pH of a coloured substance such as red ink.why?

earnstyle [38]

There are 3 possible ways of determining pH.
1. A pH meter, 2. Litmus paper/ pH test strips or 3. Titrations.

1. A pH meter works by sending a small electric current through the solution. An electrical current can only be created if there are free-moving particles such as H+ ions from an acid or OH- ions from a base. The pH meter can determine the pH by how high the conductivity is.

2. Litmus Paper or pH test strips are strips that turn a specific colour under a specific pH. This colour can then be compared to a colour chart which will tell you the pH. The downfall of this method is that the red ink will stain the strip and you will be unable to get an accurate reading.

3. A titration is the best method, if done properly, for determining pH.

4 0

3 years ago

acetylene gas c2h2 undergoes combustion to produce carbon dioxide and water vapor How many grams of water are produced by the sa

ella [17]

Answer: The amount of water produced in the given reaction is $0.692x$ grams.

Explanation:

Let us assume that the initial amount of acetylene gas given be 'x' grams. Now, to calculate the number of moles, we will use the formula:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ....(1)

Given mass of acetylene = x grams

Molar mass of acetylene = 26 g/mol

Putting values in above equation, we get:

$\text{Number of moles of acetylene}=\frac{xg}{26g/mol}=\frac{x}{26}mol$

The reaction of combustion of acetylene is given by the equation:

$2C_2H_2+5O_2\rightarrow 4CO_2+2H_2O$

By Stoichiometry of the reaction:

2 moles of acetylene produces 2 moles of water.

So, $\frac{x}{26}$ moles of acetylene will produce = $\frac{2}{2}\times \frac{x}{26}=\frac{x}{26}$ moles of water.

Now, to calculate the amount of water produced, we use equation 1:

Molar mass of water = 18 g/mol

Moles of water = $\frac{x}{26}mol$

Putting values in equation 1, we get:

$\frac{x}{26}mol=\frac{\text{Mass of water}}{18g/mol}$

$\text{Mass of water}=\frac{x}{26}\times 18=0.692x$ grams

8 0

3 years ago

Strong acids are those that ionizes almost completely in water. to be considered a strong acid, an acid must have an acid ioniza

quester [9]

Ka is the equilibrium constant for the ionization for a reaction. It is calculated as follows
ka is equal to (H3o ions)(A-) divided by (HA)
2.00x106i s equal to 0.153x0.153 divided by ( HA)
(2.00x106)HA is equal to 0.023409
HA concentration is therefore equal to 0.023409/2.00x106 which is 1.104x10^-4moles/litre

8 0

4 years ago

How much of a sample remains after five half-lives have occurred?

timama [110]

Answer:

1/32 of the original sample

Explanation:

We have to use the formula

N/No = (1/2)^t/t1/2

N= amount of radioactive sample left after n number of half lives

No= original amount of radioactive sample present

t= time taken for the amount of radioactive samples to reduce to N

t1/2= half-life of the radioactive sample

We have been told that t= five half lives. This implies that t= 5(t1/2)

N/No = (1/2)^5(t1/2)/t1/2

Note that the ratio of radioactive samples left after time (t) is given by N/No. Hence;

N/No= (1/2)^5

N/No = 1/32

Hence the fraction left is 1/32 of the original sample.

3 0

3 years ago