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4 years ago

How can matter change a liquid to a solid?

1 answer:

5 0

Heat is probably the easiest energy you can use to change your physical state. The atoms in a liquid have more energy than the atoms in a solid. There is a special temperature for every substance called the melting point. When a solid reaches the temperature of its melting point, it can become a liquid.

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A voltaic cell is constructed with two silver-silver chloride electrodes, where the half-reaction is AgCl (s) + e− → Ag (s) + Cl

ANTONII [103]

Answer : The cell emf for this cell is 0.118 V

Solution :

The half-cell reaction is:

$AgCl(s)+e^\rightarrow Ag(s)+Cl^-(aq)$

In this case, the cathode and anode both are same. So, $E^o_{cell}$ is equal to zero.

Now we have to calculate the cell emf.

Using Nernest equation :

$E_{cell}=E^o_{cell}-\frac{0.0592}{n}\log \frac{[Cl^{-}{diluted}]}{[Cl^{-}{concentrated}]}$

where,

n = number of electrons in oxidation-reduction reaction = 1

$E_{cell}$ = ?

$[Cl^{-}{diluted}]$ = 0.0222 M

$[Cl^{-}{concentrated}]$ = 2.22 M

Now put all the given values in the above equation, we get:

$E_{cell}=0-\frac{0.0592}{1}\log \frac{0.0222M}{2.22M}$

$E_{cell}=0.118V$

Therefore, the cell emf for this cell is 0.118 V

4 0

3 years ago

Balance the following chemical equations

const2013 [10]

Answer:

1) 3Fe + 2O(2, this is the subscript) - Fe(3)O(4)

2) 2Sr + O(2) - 2SrO

3) Sn + 2NaOH - Na(2)SnO(2) + H(2)

4) 2K + Br(2) -2KBr

5) 2C(8)H(18) + 25O(2) - 16CO(2) + 18H(2)O

6 0

3 years ago

Melamine is used for making

vodomira [7]

Answer:

Melamine is used for making tableware,cooking utensils, plates, plastic products etc.

Explanation:

Melamine is used to manufacture many products. How? Well melamine-formaldehyde resin, as it's full name, forms molecular structures that are molded, with heat, to take the shape of the items such as tableware.

After this chemical reaction takes place, the "left over" remains as plastic.

_________________________________________________

And so, it is used in products such as cooking utensils, plates, plastic products etc.

3 0

4 years ago

This is the net ionic equation for the complete neutralization of a generic diprotic acid with sodium hydroxide: H2A (aq) + 2 Na

kupik [55]

Answer:

c. 2 OH⁻(aq) + 2 H⁺(aq) ⇒ 2 H₂O(l)

Explanation:

Step 1: Write the molecular equation

The molecular equation includes all the molecular species.

H₂A(aq) + 2 NaOH(aq) ⇒ Na₂A(aq) + 2 H₂O(l)

Step 2: Write the complete ionic equation

The complete ionic equation includes all the ions and the molecular species.

2 H⁺(aq) + A²⁻(aq) + 2 Na⁺(aq) + 2 OH⁻(aq) ⇒ 2 Na⁺(aq) + A²⁻(aq) + 2 H₂O(l)

Step 3: Write the net ionic equation

The net ionic equation includes only the ions that participate in the reaction and the molecular species.

2 OH⁻(aq) + 2 H⁺(aq) ⇒ 2 H₂O(l)

7 0

3 years ago

A 7.300 gram sample of aluminum was quantitatively combined with a sample of selenium to form a compound. The compound weighed 3

adelina 88 [10]

Answer:

The empirical formula is Al2Se3

Explanation:

Step 1: Data given

Mass of the sample of aluminium = 7.300 grams

Mass of the compound = 39.35 grams

Molar mass of aluminium = 26.98 g/mol

Molar mass of selenium = 78.96 g/mol

Step 2: Calculate mass of selenium

Mass of selenium = mass of compound - mass of aluminium

Mass of selenium = 39.35 - 7.3 = 32.05 grams

Step 3: Calculate moles of Al

Moles Al = Mass Al/ Molar mass Al

Moles Al = 7.300 grams / 26.98 g/mol

Moles Al = 0.2706 moles

Step 4: Calculate moles of Se

Moles Se = Mass Se / Molar mass Se

Moles Se =32.05 g / 78.96 g/mol

Moles Se = 0.4059 moles

Step 5: Divide through the smallest amount of mol

Aluminium: 0.2706 / 0.2706 = 1

Selenium: 0.4059/0.2706 = 1.5

This means for each mol aluminium, we have 1.5 moles of selenium

For each 2 moles of aluminium, we have 3 moles of selenium

The empirical formula is Al2Se3

This is aluminium(III) selenide.

8 0

3 years ago