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3 years ago

How many neutrons does element X have if its atomic number is 23 and its mass number is 87?

2 answers:

6 0

The periodic table, surprisingly, carries much more info than most would think. Each item is in a specific place that accurately puts it into several precise categories at once, which scientists utilize constantly.

In this case, one of those categories is the atomic number and mass number. These together hod the key to finding out the composition of the nucleus.
The atomic number in elements is how many protons are in the nucleus. As you should know, a nucleus contains BOTH protons and neutrons. This is what is represented by the MASS number, which is protons +neutrons. (ignoring anything after the decimal point)

So, if Element has an atomic number (protons) of 23, and a mass number of 87, this means 23+neutrons=87. Do the inverse. 87-23=64
This means element X has 23 protons, 64 neutrons, and 23 electrons (assuming it's electrically neutral).

The answer of neutrons is 64
Hope this helps!

snow_lady [41]3 years ago

5 0

Answer:
100

The atomic mass of an element can be thought of as the number of protons + the number of neutrons. The atomic number of an element equals the amount of protons it has. Using this, we see that the number of neutrons can be calculated by subtracting the atomic number from the atomic mass. In this case, we get
153
−
53
=
100
.

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3 years ago

Phthalates used as plasticizers in rubber and plastic products are believed to act as hormone mimics in humans. The value of ΔHc

jeka94

Answer:

$T_f$ = 25.05°C

Explanation:

Given:

the value of ΔHcomb (heat of combustion) for dimethylphthalate (C10H10O4) is = 4685 kJ/mol.

mass = 0.905g of dimethylphthalate

molar mass = 194.18g dimethylphthalate

number of moles of dimethylphthalate = ???

$T_i$ = 21.5°C

$C_{calorimeter}$ = 6.15 kJ/°C

$T_f$ = ???

since we have our molar mass and mass of dimethylphthalate ;we can determine the number of moles as;

0.905g of dimethylphthalate × $\frac{1 mole (dimethylphthalate)}{194.184g(dimethylphthalate)}$

number of moles of dimethylphthalate = 0.000466 moles

Heat released = moles of dimethylphthalate × heat of combustion

= 0.000466 moles × 4685 kJ

= 21.84 kJ

∴ Heat absorbed by the calorimeter = $C_{calorimeter}$ $(T_f-T_i} )$

21.84 kJ =6.15 kJ/°C $* (T_f-21,5^0C)$

21.84 KJ = $(6.15 kJ/^0C * T_f) - (6.15 kJ/^0C*21.5^0C)$

21.84 KJ = $(6.15 kJ/^0C * T_f)$ - 132.225 kJ

21.84 KJ + 132.225 kJ = $(6.15 kJ/^0C * T_f)$

154.065 kJ = $(6.15 kJ/^0C * T_f)$

$T_f$ = $\frac{154.065kJ}{6.15kJ/^0C}$

$T_f$ =25.05°C

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3 years ago

What is dynamic equilibrium? What is dynamic equilibrium? Dynamic equilibrium in a chemical reaction is the condition in which t

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Answer:

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Explanation:

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Some other properties of dynamic equilibrium are:

Chemical equilibrium are attained is closed system.
The macroscopic remains constant like: volume, pressure, energy etc.
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Answer:

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