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3 years ago

What does the atomic number represents

Chemistry

2 answers:

bezimeni [28]3 years ago

8 0

the number of protons in the nucleus in an atom

drek231 [11]3 years ago

5 0

Answer:

the atomic number represents the number of protons an atom has.

You might be interested in

Which trend is observed as the first four elements in Group 17 on the Periodic Table are considered in order of increasing atomi

Katen [24]

دعنا نذهب نعم نعم نعم هذا ليس davaby ذلك طفلي

4 0

3 years ago

Calcium must lose two electrons to get a full outer shell. what is the name of the group to which calcium belongs

11111nata11111 [884]

The answer to this question would be: alkaline earth metal

Alkali earth metal is the second column group of the periodic table. In this group, the element has 2 extra electrons in their outer cells. That is why most of this metal has 2+ charge.
Their neighbor is the alkali metal which was the first column of the periodic table. The name is similar so don't confused and mix them each other.

4 0

4 years ago

A Cu2+ solution is prepared by dissolving a 0.4749 g piece of copper wire in acid. The solution is then passed through a Walden

Luda [366]

Answer:

Concentration of $Cr_2O_7^{2-}$ = 0.03101 M

Concentration of $MnO_4^-$ = 0.03721 M

Explanation:

The reduction for $Cr_2O_7^{2-}$ is;

$Cr_2O_7^{2-} + 14 H ^+ _{(aq)} + 6 e^- -----> 2 Cr^{3+} _{(aq)}+7H_2O _{(l)}$

$Cu^+_{(aq)} -----> Cu^{2+} _{(aq)} + 1 e^-$

6 moles of $Cu ^+$ = 1 mole of $Cr_2O_7^{2-}$

number of moles of Cu reacted = $\frac{mass \ of \ Cu \ wire }{ molecular weigh tof \ Cu wire }$

number of moles of Cu reacted = $\frac{0.4749}{63.55}$

number of moles of Cu reacted = 0.00747 mole

number of moles of $Cr_2O_7^{2-}$ reacted = $\frac{0.00747}{6}$

number of moles of $Cr_2O_7^{2-}$ reacted = 0.001245 mole

Concentration of $Cr_2O_7^{2-}$ = $\frac{number \ of moles }{Volume}$

Given that the volume = 40.15 mL = $40.15 *10^{-3}$ ; we have:

Concentration of $Cr_2O_7^{2-}$ = $\frac{0.001245}{40.15*10^{-3}}$

Concentration of $Cr_2O_7^{2-}$ = 0.03101 M

The reduction for $MnO_4^-$ is;

$MnO_4^- + 8H^+ + 5 e^- -----> Mn^{2+} + 4H_2O$

$Cu^+_{(aq)} -----> Cu^{2+} _{(aq)} + 1 e^-$

5 moles of $Cu ^+$ = 1 mole of $Cr_2O_7^{2-}$

number of moles of Cu reacted = $\frac{mass \ of \ Cu \ wire }{ molecular weigh tof \ Cu wire }$

number of moles of Cu reacted = $\frac{0.4749}{63.55}$

number of moles of Cu reacted = 0.00747 mole

number of moles of $MnO_4^-$ reacted = $\frac{0.00747}{5}$

number of moles of $MnO_4^-$ reacted = 0.001494 mole

Concentration of $MnO_4^-$ = $\frac{number \ of moles }{Volume}$

Given that the volume = 40.15 mL = $40.15 *10^{-3}$ ; we have:

Concentration of $MnO_4^-$ = $\frac{0.001494 }{40.15*10^{-3}}$

Concentration of $MnO_4^-$ = 0.03721 M

3 0

4 years ago

Standard reduction potentials for zinc(II) and copper(II) The standard reduction potential for a substance indicates how readily

givi [52]

The question is incomplete, the complete question is:

Standard reduction potentials for zinc(II) and copper(II)

The standard reduction potential for a substance indicates how readily that substance gains electrons relative to other substances at standard conditions. The more positive the reduction potential, the more easily the substance gains electrons. Consider the following:

Zn2+(aq)+2e−→Zn(s),Cu2+(aq)+2e−→Cu(s), E∘red=−0.763 V E∘red=+0.337 V

Part B

What is the standard potential, E∘cell, for this galvanic cell? Use the given standard reduction potentials in your calculation as appropriate.

Express your answer to three decimal places and include the appropriate units.

Answer:

1.100 V

Explanation:

E∘cell= E∘cathode - E∘anode

E∘cathode= +0.337 V

E∘anode= −0.763 V

E∘cell= 0.337-(-0.763)

E∘cell= 1.1V

4 0

3 years ago

What is the molality of a solution made by dissolving 2 moles of NaOH in 10<br> kg of water?

zaharov [31]

Answer:

0.2mol/kg

Explanation:

molality is the concentration of a solution in moles of solute per kilogram of solvent

moles of solute (NaOH) = 2moles

mass of solvent in kg. =10kg

Therefore molality. = 2moles/10 kg

=0.2mol/kg

5 0

3 years ago