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3 years ago

A eraser has a mass of 4g and a volume of 2cm3 what is it’s density

Chemistry

1 answer:

sladkih [1.3K]3 years ago

4 0

Answer:

<h3>The answer is 2.0 g/cm³</h3>

Explanation:

The density of a substance can be found by using the formula

$density = \frac{mass}{volume} \\$

From the question

mass = 4 g

volume = 2 cm³

We have

$density = \frac{4}{2} \\$

We have the final answer as

Hope this helps you

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Manganese dioxide (MnO2(s), Hf = –520.0 kJ) reacts with aluminum to form aluminum oxide (AI2O3(s), Hf = –1699.8 kJ/mol) and mang

Temka [501]

Answer : The enthalpy of the reaction = -1839.6 KJ

Solution : Given,

$\Delta (H_{f})_{MnO_{2}}$ = -520.0 KJ/mole

$\Delta (H_{f})_{Al_{2}O_{3}}$ = -1699.8 KJ/mole

The balanced chemical reaction is,

$3MnO_{2}(s)+4Al(s)\rightarrow 2Al_{2}O_{3}(s)+3Mn(s)$

Formula used :

$\Delta (H_{f})_{reaction}=\sum n(\Delta H_{f})_{product}-\sum n(\Delta H_{f})_{reactant}$

$\Delta (H_{f})_{reaction}=(2\times \Delta H_{Al_{2}O_{3}(s)}+3\times \Delta H_{Mn(s)} )-(3\times \Delta H_{MnO_{2}(s) }+4\times\Delta H_{Al}(s))$

We know that the standard enthalpy of formation of the element is equal to Zero.

Therefore, the enthalpy of formation of (Mn) and (Al) is equal to zero.

Now, put all the values in above formula, we get

$\Delta (H_{f})_{reaction}=[2moles\times (-1699.8 KJ/mole)}+3moles\times (0\text{ KJ/mole}})]-[(3moles\times(-520.0KJ/mole }+4moles\times(0\text{ KJ/mole})]$

= (-3399.6) + (1560)

= -1839.6 KJ

5 0

3 years ago

A public School district furnishes pencils to its elementary school. The pencils the secretary orders from the district warehous

const2013 [10]

Answer:

The minimum number of boxes of pencils to be ordered is 630 boxes.

Explanation:

Since a pupil uses averagely 9.3 pencils

and a box contains 12 pencils,

the school enrollment is also 812

school's enrollment x average use of pencil per student

__________________________________________

number of pencils in a box

812 x 9.3 = 7551.6

7551.6 /12 = 629.3

Having a total number of 630 boxes of pencils to be ordered.

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3 years ago

When a person in the hospital is given fluids intravenously, the fluid is typically a saline (salt) solution with about the same

Sati [7]

Answer:

Swelling of the red blood cells occurs.

Explanation:

<u>Distilled water makes the blood hypotonic ,. that is a less concentrated solution, to the body tissues including the red blood cells. </u>
Therefore the water will enter the red blood cells and may cause them to lyse or swell.
<em>Additionally , water will enter the tissue spaces and cause sweling. </em>
But in the case of a hypertonic solution , ( a salt or saline solution ) , <em>This swelling does not happen because the concentration of the saline will be equal or more than the blood. </em>
Thus the water will flow only from the blood to the solution. <u>This will not cause swelling.</u>
But too much of salt is also not recommended.

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3 years ago

What is the pOH of .12 M HNO3.

Klio2033 [76]

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3 years ago

The reaction of chlorine

KengaRu [80]

The reaction of chlorine
gas with solid phosphorus produces solid phosphorus pentachloride
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3 years ago