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saul85 [17]
2 years ago
15

750.0g of water that was just boiled (heated to 100.0/c loses 78.45KJ of heat as it cools.What is the final temperature of water

?
Chemistry
1 answer:
Iteru [2.4K]2 years ago
4 0
  • Mass=m=750g=0.75kg
  • Q=78.45\times 10^3J=78450J
  • T_i=100°C
  • T_f=?
  • Specific heat capacity=c=4200J/kg°C

According to thermodynamics

\\ \tt\bull\rightarrowtail Q=mc\Delta T

\\ \tt\bull\rightarrowtail Q/mc=\Delta T

\\ \tt\bull\rightarrowtail \Delta T=\dfrac{78450}{0.75(4200)}

\\ \tt\bull\rightarrowtail \Delta T=24.9°C

\\ \tt\bull\rightarrowtail T_i-T_f=24.9

\\ \tt\bull\rightarrowtail T_f=100-24.9=76.1°C

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3 years ago
A voltaic cell is created by using a copper cathode and a magnesium anode. The cathode is immersed in a solution of Cu2 ions, an
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As the reaction proceeds in the given voltaic cell, the Na₂SO₄ present in the salt bridge will dissociate into Na⁺ and SO₄²⁻ ions. As the copper ions in the solution are being deposited on the copper cathode as neutral copper atoms, the solution will become more negative, therefore the Na⁺ ions in the salt bridge will migrate into the the solution in order to maintain electrical neutrality. At the anode, as the Mg metal dissolve into the solution as Mg⁺² ions, the  solution will tend to become more positive. Therefore, the SO₄²⁻ ions present in the salt bridge will migrate into the solution in order to maintain electrical neutrality.

Explanation:

A voltaic or galvanic cell is an example of an electrochemical cell.

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The voltaic cell uses two different metal electrodes each immersed in an electrolyte solution. The two electrodes are connected to each other by means of a wire which allows the flow of electrons from the anode to the cathode. The electrolytes are connected by means of a salt bridge which is a junction that connects the electrolytic solution in the anode and cathode compartment. The salt bridge usually consists of a strong electrolyte like NaCl, KCl, Na₂SO₄, etc.

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5 0
3 years ago
HELP!
ki77a [65]

Answer:

(1)There are 1.5 moles of water in a 27 gram sample of water. The molar mass of water is 18.02 gmol g m o l .(2)

AnswersChemistryGCSEArticle

What is the mass (g) of 0.25mols of NaCl?

What you need for these equations are a calculator, periodic table and the following equation:

Mass (g) = Mr x Moles (important equation to remember)

In this case we already know the moles as it's in the question, 0.25 moles.

to find the Mr, you need to look at your periodic table. Find the relative atomic mass of Na and Cl and add the two numbers together.

Na = 22.99

Cl = 35.45

NaCl = 58.4

Now just put all of the numbers into the equation.

0.25 x 58.4 = 14.6g

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