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3 years ago

9

Why does the ice melt when you hold it in your hand? A.Heat is transferred from your hand to the ice cube. B.Heat from the ice c

ube is transferred to your hand. C.The ice cube radiates heat to your hand. D.Your hand transfers temperature to the ice cube.

1 answer:

Thepotemich [5.8K]3 years ago

3 0

A. Heat is transferred from your hand to the ice cube.

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When 2.3 × 10^3 g of CaCO3 are heated, the actual yield of CaO is 1.09 × 10^3g. What is

iren [92.7K]

The percent yield : 4. 84.58%

<h3>Further explanation</h3>

Reaction

CaCO₃ ⇄ CaO+CO₂

mass CaCO₃ = 2.3 × 10³ g

mol CaCO₃ (MW=100.0869 g/mol) :

$\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{2.3\times 10^3}{100,0869}\\\\mol=22.98$

From the equation, mol CaCO₃ : CaO = 1 : 1, so mol CaO=22.98

mass CaO(MW=56.0774 g/mol)⇒ (theoretical) :

$\tt mass=mol\times MW\\\\mass=22.98\times 56,0774\\\\mass=1288.659~g$

The percent yield :

$\tt \%yield=\dfrac{actual}{theoretical}\times 100\%\\\\\%yield=\dfrac{1090}{1288.659}\times 100\%\\\\\5yield=84.58\%$

5 0

3 years ago

Click on the event or events that led to the formulation of the cell theory

Alexandra [31]

So back in 1665 Robert hook was able to view cells and describe them along with pictures, the reason he was able to see cells was because the microscope was invented a bit before, which allowed him to think about things differently, he was looking at a cork and saw squared objects, these objects were cells, according to him.

So while the cork was the reason he discovers cells on it in the first place,
The microscope was what allowed him to do that

So it’s (HOOKE LOOKING AT A CORK)
And it’s (THE INVENTION OF THE MICROSCOPE)

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3 years ago

A student mixed a small amount of iron filings and sulphur powder in a dish. He could not

Temka [501]

Answer:

$\huge \boxed{\mathrm{Carbon \ disulphide}}$

Explanation:

Carbon disulphide is the liquid that can be used to separate iron fillings and sulphur powder.

When carbon disulphide is poured into the dish, the sulphur powder gets easily dissolved in the carbon disulfide. The iron fillings are left to settle on the bottom of the dish.

The iron fillings can get seperated through filtration. When the mixture of sulphur powder and carbon disulphide gets completely evaporated, the sulphur powder is left over.

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3 years ago

1) The heat of combustion for the gases hydrogen, methane and ethane are −285.8, −890.4 and −1559.9 kJ/mol respectively at 298K.

Morgarella [4.7K]

Answer:

The enthalpy of the reaction is 64.9 kJ/mol.

Explanation:

$H_2 + \frac{1}{2}O_2\rightarrow H_2O,\Delta H_1 =-285.8 kJ$ ..[1]

$CH_4 + 2O_2\rightarrow CO_2 + 2H_2O,\Delta H_2 =-890.4 kJ$ ..[2]

$C_2H_6 + \frac{7}{2}O_2\rightarrow 2CO_2 + 3H_2O,\Delta H_3= -1559.9 kJ$ ..[3]

$2CH_4(g)\rightarrow C_2H_6(g) + H_2(g),\Delta H_4=?$ ..[4]

2 × [2] - [1]- [3] = [4] (Using Hess's law)

$\Delta H_4=2\times \Delta H_2 -\Delta H_1 -\Delta H_3$

$\Delta H_4=2\times (-890.4 kJ)-(-285.8 kJ) -(-1559.9 kJ)$

$\Delta H_4=64.9 kJ/mol$

The enthalpy of the reaction is 64.9 kJ/mol.

3 0

3 years ago

Mechanical Advantage may be calculated using all of the following except ___.

kotegsom [21]

The only exception of calculating mechanical advantage is by multiplying resistance force by effort force. For example, in calculating the mechanical advantage of a lever, we consider its output and input forces. The equation would now be as follows:

Mechanical advantage = output force / input force

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3 years ago