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3 years ago

What is the mass of an element with 78 protons and 78 neutrons

Chemistry

2 answers:

stepan [7]3 years ago

8 0

Mass number=number of protons+number of neutrons
so mass number of the element you stated = 78+78 = 156 au

Reika [66]3 years ago

4 0

156. Atomic mass if the number of protons and neutrons within an atom.

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A partir de que materiales se obtienen los metales? en que se diferencian?

Anon25 [30]

Los metales son materiales que se obtienen a partir de minerales que forman parte de las rocas. Por ejemplo, el metal hierro se extrae de minerales de hierro como la magnetita o la siderita.

6 0

3 years ago

Read 2 more answers

"A crosslinked copolymer consists of 57 wt% ethylene (C2H4) repeat units and 43 wt% propylene (C3H6) repeat units. Determine the

ch4aika [34]

Explanation:

Percentage ethylene by weight = 57%

Percentage propylene by weight = 43%

Suppose in 100 grams of polymer:

Mass of ethylene = 57 g

Mass of propylene = 43 g

Moles of ethylene = $\frac{57 g}{28 g/mol}=2.036 mol$

Moles of propylene = $\frac{43g}{42g/mol}=1.024 mol$

1 mole = $N_A =6.022\times 10^{23}$ molecules/ atoms

Units of ethylene = $2.036 mol\times N_A$

Units of propylene = $1.024 mol\times N_A$

a) Fraction of ethylene units:

$=\frac{2.036 mol\times N_A}{2.306 mol\times N_A+1.024 mol\times N_A}=\frac{509}{765}$

b ) Fraction of propylene units:

$=\frac{1.024mol\times N_A}{2.306 mol\times N_A+1.024 mol\times N_A}=\frac{256}{765}$

3 0

3 years ago

How many seconds are there in 23 days ?

Brrunno [24]

Since there are 23 days and 24 hours in each day, you multi-ply them and get 552 hours. Since each hours is 60 minutes, 552*60 is 33120 minutes. Since one minute is 60 seconds, 60*33120 is 1,987,200 seconds. Therefore, there are 1,987,200 seconds in 23 days.

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3 years ago

The solubility of water in diethyl ether has been reported to be 1.468 % by mass.' Assuming that 23.0 mL of diethyl ether were a

melomori [17]

Explanation:

As it is given that solubility of water in diethyl ether is 1.468 %. This means that in 100 ml saturated solution water present is 1.468 ml.

Hence, amount of diethyl ether present will be calculated as follows.

(100ml - 1.468 ml)

= 98.532 ml

So, it means that 98.532 ml of diethyl ether can dissolve 1.468 ml of water.

Hence, 23 ml of diethyl ether can dissolve the amount of water will be calculated as follows.

Amount of water = $\frac{1.468 ml \times 23 ml}{98.532 ml}$