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3 years ago

List 4 physical properties of each of the following:

1 answer:

4 0

<span>Copper wire - Tensile strength. Coefficient of thermal expansion, Thermal conductivity, Corrosion resistance.

500g of Butter - density, volume, color and smell

Glass of Milk - white color, smell, taste and volume

Candle - size, shape, color and density

Piece of Aluminum foil - melting point, electrical conductivity, thermal conductivity, electrical resistivity

Spoon of sugar - texture, melting point, boiling point, color

Toothpaste - taste, smell, abrasiveness, cohesiveness</span>

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In terms of energy, how would you classify the following chemical reaction?

olga_2 [115]

1. Answer;

- Exothermic reaction

Explanation;

-Exothermic reactions are types of chemical reactions in which heat energy is released to the surroundings. Since enthalpy change is the difference between the energy of products an that of reactants. It means that in an exothermic reaction the energy of products is less than that of products. In this case an energy of 315kJ is released to the surroundings.

2. Answer;

Conserved

-The total amount of energy before and after a chemical reaction is the same. Thus, energy is conserved.

Explanation;

-According to the law of conservation of energy, energy is neither created nor destroyed. Energy may change form during a chemical reaction. For example, energy may change form from chemical energy to heat energy when gas burns in a furnace. However, the exact amount of energy remains after the reaction as before, which is true for all chemical reactions.

3 0

3 years ago

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The useful metal manganese can be extracted from the mineral rhodochrosite by a two-step process.... In the first step, manganes

frez [133]

Answer : The mass of $MnCO_3$ required are, 35 kg

Explanation :

First we have to calculate the mass of $MnO_2$ .

The first step balanced chemical reaction is:

$2MnCO_3+O_2\rightarrow 2MnO_2+2CO_2$

Molar mass of $MnCO_3$ = 115 g/mole

Molar mass of $MnO_2$ = 87 g/mole

Let the mass of $MnCO_3$ be, 'x' grams.

From the balanced reaction, we conclude that

As, $(2\times 115)g$ of $MnCO_3$ react to give $(2\times 87)g$ of $MnO_2$

So, $xg$ of $MnCO_3$ react to give $\frac{(2\times 87)g}{(2\times 115)g}\times x=0.757xg$ of $MnO_2$

And as we are given that the yield produced from the first step is, 65 % that means,

$60\% \text{ of }0.757xg=\frac{60}{100}\times 0.757x=0.4542xg$

The mass of $MnO_2$ obtained = 0.4542x g

Now we have to calculate the mass of $Mn$ .

The second step balanced chemical reaction is:

$3MnO_2+4Al\rightarrow 3Mn+2Al_2O_3$

Molar mass of $MnO_2$ = 87 g/mole

Molar mass of $Mn$ = 55 g/mole

From the balanced reaction, we conclude that

As, $(3\times 87)g$ of $MnO_2$ react to give $(3\times 55)g$ of $Mn$

So, $0.4542xg$ of $MnO_2$ react to give $\frac{(3\times 55)g}{(3\times 87)g}\times 0.4542x=0.287xg$ of $Mn$

And as we are given that the yield produced from the second step is, 80 % that means,

$80\% \text{ of }0.287xg=\frac{80}{100}\times 0.287x=0.2296xg$

The mass of $Mn$ obtained = 0.2296x g

The given mass of Mn = 8.0 kg = 8000 g (1 kg = 1000 g)

So, 0.2296x = 8000

x = 34843.20 g = 34.84 kg = 35 kg

Therefore, the mass of $MnCO_3$ required are, 35 kg

4 0

3 years ago

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Which mineral can be found in the rocks phyllite, sandstone, and granite?

Dominik [7]

Answer:

1 quartz

Explanation:

pls tell me if I'm wrong

6 0

3 years ago

Read 2 more answers

For molecules with more than one ionizable groups, such as glycine, which of the following statements is true? For molecules wit

tester [92]

Answer: Option (a) is the correct answer.

Explanation:

The isoelectric point (pI) is actually the pH where a particular amino acid exists as a neutral molecule. This means that if pH equals pI then there will be no electric charge on the molecule.

Therefore, the statement at pH near the pI, nearly all the molecules carry no net charge, is true.

A buffer is composed of a solution of weak acid or base and salt of weak acid/base.So, when pH equals pI then there occurs no net charge. Hence, there will be no existence of conjugate acid-base pair.

Therefore, the statement when the pH is near the pI, the solution is near its maximum buffering ability, is false.

It is known that when pH is less than pI then there will be a net positive charge on the amino acid.

Hence, the statement at a pH near the pI, nearly all the molecules carry a net positive charge, is false.

When pH is greater than pI then amino acid will have a net negative charge. Hence, the statement at a pH near the pI, nearly all the molecules carry a net negative charge, is false.

Thus, we can conclude that out of the given options the statement at pH near the pI, nearly all the molecules carry no net charge, is true.

5 0

3 years ago

How do doctors know that Lyme disease is caused by a bacterium and NOT a virus?

Savatey [412]

Answer: Doctors can diagnose the disease through physical findings such as a "bull's-eye" rash along with a history of symptoms. But not everyone has the rash, and not everyone can recall being bitten. Special blood tests can be taken three to four weeks after suspected contact to confirm the diagnosis.

Explanation: HOPE THIS HELPS HAVE A GOOD DAY!;)

5 0

3 years ago