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3 years ago

(they don't have science so I guess cemastry will do.)

Chemistry

1 answer:

DedPeter [7]3 years ago

7 0

warm air rises because of convection.

A student holds the back of his hand near an iron to see if it's hot. The heat transfer is conduction.

Warm water moves throughout a mattress because of ... why is there warm water in a mattress again? Convection, I guess.

In a swimming pool, the water near the surface is warmer because of convection and solar radiation; it's closer to the Sun than the bottom of the pool, so it receives more thermal radiation, making it warmer.

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5.11 g of MgSO₄ is placed into 100.0 mL of water. The water's temperature increases by 6.70°C. Calculate ∆H, in kJ/mol, for the

cupoosta [38]

Answer: Thus ∆H, in kJ/mol, for the dissolution of MgSO₄ is -66.7 kJ

Explanation:

To calculate the entalpy, we use the equation:

$q=mc\Delta T$

where,

q = heat absorbed by water = ?

m = mass of water = ${\text {volume of water}}\times {\text {density of water}}=100.0ml\times 1.00g/ml=100.0g$

c = heat capacity of water = 4.186 J/g°C

$\Delta T$ = change in temperature = $6.70^0C$

$q=100.0g\times 4.184J/g^0C\times 6.70^0C=2803.3J=2.8033kJ$

Sign convention of heat:

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

The heat absorbed by water will be equal to heat released by $MgSO_4$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass = 5.11 g

Molar mass = 120 g/mol

Putting values in above equation, we get:

$\text{Moles of }MgSO_4=\frac{5.11g}{120g/mol}=0.042mol$

0.042 moles of $MgSO_4$ releases = 2.8033 kJ

1 mole of $MgSO_4$ releases = $\frac{2.8033 kJ}{0.042}\times 1=66.7kJ$

Thus ∆H, in kJ/mol, for the dissolution of MgSO₄ is -66.7 kJ

3 0

3 years ago

NaNO3 ———> **heat above the arrow**

yanalaym [24]

Answer:

D (Decomposition)

Explanation:

This reaction is a decomposition reaction because one substance (NaNO3) is being separated into two substances (NaNO2 and O2). Alternatively, you could use the process of elimination. The reaction can't be single/double replacement because there's only one reactant, it can't be synthesis because substances are being broken down, not formed, and it can't be combustion because O2 is a product, not a reactant, and CO2 and H2O aren't being produced, as is common with combustion reactions.

4 0

3 years ago

What are the different elements found in naphthalene and how many atoms of each are found in the formula. C10H8

Alex777 [14]

Calculating the molar mass of naphthalene (C10H8)

molar mass = 10 x (12.01) + 8(1.008)

= 120.1 + 8.064 = 128.164 g/mol

8 0

3 years ago

Two significance of melting point

eimsori [14]

The significance of melting points are

it gives us a idea about inter molecular force which binds the particles together.

at melting point the solid and liquid states exist in equilibrium.

<h3>What is melting point?</h3>

The melting point is the temperature at which a given substance change its physical state from solid to liquid. At this point solids and liquids exist at equilibrium. Melting point of a substance depends on pressure. The melting point of ice increases when pressure decreases. Melting point of a substance decreases by the presence of impurities in it. so you increase or decrease the melting point on any substance by adding more impurities. Ionic bonds, shape and size of molecules are some other factors that affect the melting point.

To learn more about melting point refer:

brainly.com/question/25689052

#SPJ2

5 0

2 years ago

Lithium hydroxide is used in alkaline batteries. Calculate the molarity of a solution prepared by dissolving 1.495 moles of LiOH

Mashcka [7]

Answer:

[LiOH] = 1.99M

Explanation:

We can apply this rule of three to determine the molarity of LiOH

Molarity are the moles of solute (in this case, LiOH) that are contained in 1L of solution. Our solution's volume is 750 mL

We convert the volume to L → 750 mL . 1L / 1000mL = 0.750L

Therefore we propose:

In 0.750L we have 1.495 moles of LiOH

In 1L we may have (1 . 1.495) /0.750 = 1.99 moles

Molarity → mol/L

4 0

3 years ago