All categories

3 years ago

= 25 X 5 = (use the correct number of sig figs)

Chemistry

1 answer:

Anton [14]3 years ago

5 0

Answer:

1.25 *10^2

Explanation:

25*5 = 125

= 1.25 *10^2

You might be interested in

Sulfur has an atomic mass of 32 u and Avogadro's number is 6 × 1023 formula units/mole. The number of sulfur atoms in 1 g of sul

Vikki [24]

Answer:

The number of sulfur atoms in 1 g of sulfur is:- $1.875\times 10^{22}$ atoms

Explanation:

Avogadro’s number represent the number of the constituent particles which are present in one mole of the substance. It is named after scientist Amedeo Avogadro and is denoted by $N_0$ .

Avogadro constant:-

$N_a=6\times 10^{23}$

Given atomic mass of sulfur = 32 u

Which means that:-

32 g of sulfur contains $6\times 10^{23}$ of atoms

Also,

1 g of sulfur contains $\frac {6\times 10^{23}}{32}$ of atoms

So, The number of sulfur atoms in 1 g of sulfur is:- $1.875\times 10^{22}$ atoms

6 0

3 years ago

Combine the two half-reactions that give the spontaneous cell reaction with the smallest E∘. Fe2+(aq)+2e−→Fe(s) E∘=−0.45V I2(s)+

Iteru [2.4K]

Answer: The spontaneous cell reaction having smallest $E^o$ is $I_2+Cu\rightarrow Cu^{2+}+2I^-$

Explanation:

We are given:

$E^o_{(Fe^{2+}/Fe)}=-0.45V\\E^o_{(I_2/I^-)}=0.54V\\E^o_{(Cu^{2+}/Cu)}=0.34V$

The substance having highest positive $E^o$ potential will always get reduced and will undergo reduction reaction. Here, iodine will always undergo reduction reaction, then copper and then iron.

The equation used to calculate electrode potential of the cell is:

$E^o_{cell}=E^o_{oxidation}+E^o_{reduction}$

The combination of the cell reactions follows:

Case 1:

Here, iodine is getting reduced and iron is getting oxidized.

The cell equation follows:

$I_2(s)+Fe(s)\rightarrow Fe^{2+}(aq.)+2I^-(aq.)$

Oxidation half reaction: $Fe(s)\rightarrow Fe^{2+}(aq.)+2e^-$ $E^o_{oxidation}=0.45V$

Reduction half reaction: $I_2(s)+2e^-\rightarrow 2I_-(aq.)$ $E^o_{reduction}=0.54V$

$E^o_{cell}=0.45+0.54=0.99V$

Thus, this cell will not give the spontaneous cell reaction with smallest $E^o_{cell}$

Case 2:

Here, iodine is getting reduced and copper is getting oxidized.

The cell equation follows:

$I_2(s)+Cu(s)\rightarrow Cu^{2+}(aq.)+2I^-(aq.)$

Oxidation half reaction: $Cu(s)\rightarrow Cu^{2+}(aq.)+2e^-$ $E^o_{oxidation}=-0.34V$

Reduction half reaction: $I_2(s)+2e^-\rightarrow 2I_-(aq.)$ $E^o_{reduction}=0.54V$

$E^o_{cell}=-0.34+0.54=0.20V$

Thus, this cell will give the spontaneous cell reaction with smallest $E^o_{cell}$

Case 3:

Here, copper is getting reduced and iron is getting oxidized.

The cell equation follows:

$Cu^{2+}(aq.)+Fe(s)\rightarrow Fe^{2+}(aq.)+Cu(s)$

Oxidation half reaction: $Fe(s)\rightarrow Fe^{2+}(aq.)+2e^-$ $E^o_{oxidation}=0.45V$

Reduction half reaction: $Cu^{2+}(aq.)+2e^-\rightarrow Cu(s)$ $E^o_{reduction}=0.34V$

$E^o_{cell}=0.45+0.34=0.79V$

Thus, this cell will not give the spontaneous cell reaction with smallest $E^o_{cell}$

Hence, the spontaneous cell reaction having smallest $E^o$ is $I_2+Cu\rightarrow Cu^{2+}+2I^-$

7 0

3 years ago

The minimum energy required to start a reaction

sergeinik [125]

The answer to that question would be Activation energy. If would like me to elaborate just let me know. :)

7 0

3 years ago

Read 2 more answers

Ethanol undergoes combustion in oxygen to produce carbon dioxide gas and liquid water. The standard heat of combustion of ethano

Mama L [17]

Answer:

$-277.6\ \text{kJ/mol}$

Explanation:

Heat of combustion of $C_2H_5OH(l)$ = -1366.8 kJ/mol

Heat of formation of $CO_2(g)$ = -393.5 kJ/mol

Heat of formation of $H_2O(l)$ = -285.8 kJ/mol

The reaction is

$C_2H_5OH(l)\rightarrow 2CO_2(g)+3H_2O(l)$

Assuming $x$ is the standard enthalpy of formation of ethanol

$-1366.8=2\times (-393.5)+3\times (-285.8)-x\\\Rightarrow x=2\times (-393.5)+3\times (-285.8)+1366.8\\\Rightarrow x=-277.6\ \text{kJ/mol}$

The standard enthalpy of formation of ethanol is $-277.6\ \text{kJ/mol}$ .

5 0

3 years ago

This is how krypton appears in the periodic table.A purple box has K r at the center and 36 above. Below it says krypton and bel

GarryVolchara [31]

The number of protons in an atom of krypton is 36.

Explanation:

The number written above the symbol of Kr in the periodic table represents the atomic number of the element . Then the number written in the below represents the mass number.

So the mass number of krypton is 84 and the atomic number of krypton is 36. As it is known that number of protons and electrons will be equal in a stable element. Thus, the krypton atom will be having 36 protons.

7 0

3 years ago

Read 2 more answers