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3 years ago

Hellpppppp pls it’s due in less than 10 min

Chemistry

2 answers:

Alex777 [14]3 years ago

8 0

Can you show the whole question or type it out? i would love to help

elena-s [515]3 years ago

5 0

Answer:

Theory

Explanation:

the model of an atom, for example isnt a method, its showing a theory in which scientists have discovered and analyze particles, such as atoms. Therefore it is a theory, something that is a known fact

hope this helped:)

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Hafnium has six naturally occurring isotopes: 0.16% of 174Hf, with an atomic weight of 173.940 amu; 5.26% of 176Hf, with an atom

ser-zykov [4K]

Answer:

177.277amu

Explanation:

the total occuring isotopes for Hafnium is =6.

First isotope had an atomic weight of 173.940amu

Second isotope =175.941amu

Third isotope =176.943amu

Fourth isotope=177.944amu

Fifth isotope. =178.946amu

sixth isotope .179.947amu

Average atomic weight of Hafnium= sum of all the atomic weights of the isotopes/ Total occuring isotopes

Thus, 173.940amu+175.941amu+176.943amu+177.944amu+178.946amu+179.947amu.= 1063.661amu

Average atomic weight= 1063.661amu /6 = 177.2768333amu

= 177.277amu to 3 decimal places.

6 0

3 years ago

For each of the following circumstances, indicate whether the calculated molarity of NaOH would be lower, higher or unaffected.

irina [24]

Answer:

a)calculated molarity of NaOH would be lower

b) calculated molarity of NaOH would be lower

c) calculated molarity of NaOH would be lower

d) calculated molarity of NaOH would be unaffected

Explanation:

Let us recall that the reaction of NaOH and HCl is as follows;

NaOH(aq) + HCl(aq) ----> NaCl(aq) + H2O(l)

Since the reaction is 1:1, when the number of moles of HCl reacting with NaOH is low due to dilution, the calculated molarity of NaOH also becomes less than it's accurate value.

When 40mL of water is added to the titration flask rather than 25ml of water, the acid is more dilute hence less number of moles of acid than necessary reacts with the base thereby yielding a less than accurate value of the molarity of NaOH.

If the burette wet with water is not rinsed with NaOH solution, the concentration of the NaOH in the burette decreases due to dilution with water and a less than accuracy value is calculated for the molarity of NaOH.

If five drops of phenolphthalein is used instead of one or two drops, there is no qualms since enough phenolphthalein may be added to ensure that a sharp end point is obtained.

8 0

3 years ago

The molar mass of barium nitrate (ba(no3)2) is 261.35 g/mol. what is the mass of 5.30 × 1022 formula units of ba(no3)2? 0.0900 g

liberstina [14]

Molar mass is the ratio of the mass to that amount of the substance. The mass of the barium nitrate in the formula unit is 23.0 grams.

The mass of a substance is the product of the molar mass of the compound and the number of moles of the compound.

Given,

Molar mass of barium nitrate = 261.35 g/mol

If, $6.022 \times 10^{23}$ have a mass of 261.35 g/mol then, $5.30 \times 10^{22}$ formula units will have a mass of,