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Free_Kalibri [48]
3 years ago
13

How many neutrons are there in 9 molecules of P4 with mass number 31 and proton number 15?

Chemistry
2 answers:
aalyn [17]3 years ago
7 0

A = mass number which is equal to the total number of protons + number of neutrons, Z= atomic number of any element which is also indicates Number of protons or number of electron in the given atom.


The formula to calculate neutron would be :

mass number - proton  

31   - 15     = 16

Thus 16 neutrons are found in one atom of P  

There are 4 atom in one molecule

Thus  

4 atom /1 molecule * 9 molecule * 16 neutron / 1 atom  

= 4*9*16= 576 neutrons


Phoenix [80]3 years ago
7 0
The formula to calculate neutron would be :

mass number - proton 

31   - 15     = 16

Since it got 9 molecules, you need to multiply this by 9 , 

16 x 9  = 144

hope this helps


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Determine the limiting reactant (lr) and the mass (in g) of nitrogen that can be formed from 50.0 g n2o4 and 45.0 g n2h4. some p
Licemer1 [7]
                                                   N2O4(l) + 2 N2H4(l) → 3 N2(g) + 4 H2O(g)
1) to calculate the limiting reactant you need to pass grams to moles.
<span> moles is calculated by dividing mass by molar mass
</span>
mass of N2O4: 50.0 g 
molar mass of <span>N2O4 = 92.02 g/mol
</span><span>molar mass of N2H4 = 32.05 g/mol.
</span>mass of N2H4:45.0 g

moles N2O4=50.0/92.02 g/mol= 0,54 mol of N2O4
moles N2H4= 45/32.05 g/mol= 1,40 mol of <span><span>N2H4

</span> 2)</span>
By looking at the balanced equation, you can see that 1 mol of N2O4 needs 2 moles of N2H4 to fully react . So to react  0,54 moles of N2O4, you need 2x0,54 moles of <span>N2H4 moles
</span><span>N2H4 needed = 1,08 moles.
You have more that 1,08 moles </span><span>N2H4, so this means the limiting reagent is not N2H4, it's </span>N2O4. The molecule that has molecules that are left is never the limiting reactant.

3) 1 mol of N2O4 reacting, will produce 3 mol of N2 (look at the equation)
There are 0,54 mol of N2O4 available to react, so how many moles will produce of N2?
1 mol N2O4------------3 mol of N2
0,54 mol N2O4--------x
x=1,62 mol of N2

4) the only thing left to do is convert the moles obtained, to grams.
We use the same formula as before, moles equal to mass divided by molar mass.
moles= \frac{grams}{molar mass}             (molar mass of N2= 28)
1,62 mol of N2= mass/ 28
mass of N2= 45,36 grams

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Explanation:

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2 years ago
How many km are in 5.6mm? 5.6x103 5.6x10-6 5.6x10-3 5.6x106​
il63 [147K]

Hey there :)

<em>Q</em><em>u</em><em>e</em><em>s</em><em>t</em><em>i</em><em>o</em><em>n</em><em>:</em><em> </em><em>How many km are in 5.6mm? </em>

<em>=</em><em>></em><em>5.6x10</em><em>^</em><em>3 </em>

<em>=</em><em>></em><em>5.6x10</em><em>^</em><em>-6 </em>

<em>=</em><em>></em><em>5.6x10</em><em>^</em><em>-3 </em>

<em>=</em><em>></em><em> </em><em>5.6x10</em><em>^</em><em>6</em>

<em>A</em><em>n</em><em>s</em><em>w</em><em>e</em><em>r</em><em>:</em><em>-</em>

5.6 \times 10^{ - 6}

<em>E</em><em>x</em><em>p</em><em>l</em><em>a</em><em>n</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em>:</em><em>-</em>

By using the formula-

1millimeter =  \frac{1}{1000000}

As 1 with 6 zeros, we convert it into exponential form.

=  >  \frac{1}{10^{6} }

As this above value is fraction type, we can do the reciprocal, thus, the exponent gets a negative value.

=  > 10^{ - 6}

Now combine with given question.

=  > 5.6 \times 10^{ - 6}

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A monoprotic weak acid, HA , dissociates in water according to the reaction HA(aq)↽−−⇀H+(aq)+A−(aq) The equilibrium concentratio
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Answer:

pK_{a} of HA is 6.80

Explanation:

pK_{a}=-logK_{a}

Acid dissociation constant (K_{a}) of HA is represented as-

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Where species inside third bracket represents equilibrium concentrations

Now, plug in all the given equilibrium concentration into above equation-

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So, K_{a}=1.6\times 10^{-7}

Hence pK_{a}=-log(1.6\times 10^{-7})=6.80

6 0
3 years ago
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