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sammy [17]
3 years ago
7

If a sample of a substance contains 9.03 x 1023 representative particles, how many moles does this represent?

Chemistry
1 answer:
GaryK [48]3 years ago
5 0
I believe its 10^23 u r saying
then no. of moles= 9.03*10^23/6.02*10^23=1.5mole
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Inessa05 [86]
B. Temporary hope this helped :)
5 0
2 years ago
A 25.00 mL sample of 0.320 M KOH is titrated with 0.750 M HBr at 25 °C.
Fudgin [204]

Answer:

a. pH = 13.50

b. pH = 13.15

Explanation:

Hello!

In this case, since the undergoing chemical reaction between KOH and HBr is:

HBr+KOH\rightarrow KBr+H_2O

As they are both strong. In such a way, since the initial analyte is the 25.00 mL solution of 0.320-M KOH, we first compute the pOH it has, considering that all the KOH is ionized in potassium and hydroxide ions:

pOH=-log([OH^-])=-log(0.320)=0.50

Thus, the pH is:

pH+pOH=14\\pH=14-pOH=14-0.50\\pH=13.50

Which is the same answer for a and b as they ask the same.

Moreover, once 5.00 mL of the HBr is added, we need to compute the reacting moles of each substance:

n_{KOH}=0.02500mL*0.320mol/L=0.00800mol\\\\n_{HBr}=0.005L*0.750mol/L=0.00375mol

It means that since there are more moles of KOH, we need to compute the remaining moles after those 0.00375 moles of acid consume 0.00375 moles of base because they are in a 1:1 mole ratio:

n_{KOH}^{remaining}=0.00425mol

Next, we compute the resulting concentration of hydroxide ions (equal to the concentration of KOH) in the final solution of 30.00 mL (25.00 mL + 5.00 mL):

[OH^-]=[KOH]=\frac{0.00425mol}{0.03000L}=0.142M

So the pOH and the pH turn out:

pOH=-log(0.142)=0.849\\pH+pOH=14\\pH=14-pOH=14-0.849\\pH=13.15

Best regards!

7 0
3 years ago
Potential energy is based on an objects <br><br> A)gravity<br> B)mass<br> C)position <br> D)kinetic
ollegr [7]

Answer:

c

Explanation:

because potential energy is created with the position of a body when you pick up something the thing will have stored energy which is transferred from you so the stored energy is potential energy created by the position of a body that when you see over your head you scared of that thing not to bit you because it has stored energy if you see the thing already failed on the ground you wouldn't scared of that because the enery is already gone

Hope help you

5 0
3 years ago
In reality, energy conversion from burning fuel is never 100% efficient. Significant loss of energy due to heating occurs. If th
algol [13]

Answer:

Electrical energy = 130000000 J and Heat energy = 520000000 J

Explanation:

Multiply the amount of joules from the last question (650000000) by .20 and .80. (Which are the percentages)

6 0
2 years ago
1. An atom of an elephant has atomic mass of 39 and has number of neutrons as 20 calculate protons number.
r-ruslan [8.4K]

Answer:

See Explanation

Explanation:

1) Let us recall that;

Mass number = number of protons + number of neutrons

Where;

Number of protons = ?

Number of neutrons =20

Mass number =39

Number of protons = mass number - number of neutrons

Mass of protons =39 - 20= 19 protons

2) Atomic number = 13

Number of neutrons =14

Then the mass number =13 +14 =27

The symbol of the element is 27X13

The number of protons= the number of electrons =13

The atomic number is the same as the proton number =13

5 0
2 years ago
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