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4 years ago

How do I do question number 3? And what is the answer?

Chemistry

1 answer:

shutvik [7]4 years ago

3 0

Answer:

60.02 g.

Explanation:

It is clear from the balanced equation:

Mg + 2HCl → MgCl₂ + H₂.

that 1.0 mole of Mg reacts with 2.0 moles of HCl to produce 1.0 mole of MgCl₂ and 1.0 moles of H₂.

20.0 g of Mg reacts with excess HCl. To calculate the no. of grams of HCl that reacted, we should calculate the no. of moles of Mg:

no. of moles of Mg = mass/atomic mass = (20.0 g)/(24.3 g/mol) = 0.823 mol.

From the balanced equation; every 1.0 mol of Mg reacts with 2 moles of HCl.

∴ 0.833 mol of Mg will react with (2 x 0.833 mol = 1.646 mol) of HCl.

∴ The mass of reacted HCl = no. of moles x molar mass = (1.646 mol)(36.46 g/mol) = 60.02 g.

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32,500 joules are used to boil a sample of water at its melting point what is the mass of the water?

Ivenika [448]

Answer:

43.18 gm

Explanation:

Heat of fusion of water at 0° C is 334 j/gm

then you have to heat the water to boiling point (100 C)

specific heat of water is 4.186 j/g-c

x = grams of water

x ( 334 + 4.186 (100) ) = 32500

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2 years ago

A wooden boat is discovered just south of the Graet Pyramid in Egypt had a Carbon-14 content of approximately 25% of that found

wolverine [178]

Because 25% is half of 0.5 and the half life of ${}^{14}\text{C}$ is given as 5,715, the time it takes to reach this amount should just be double the half life: 11430 years.

However, in other cases the problem may not have easy numbers, so below is a more mathematical approach.

The half life formula is $A=A_0*(\frac{1}{2} )^{\frac{t}{h} }$ .

Solving for t gives:

$t=\frac{h*\ln(\frac{A}{A_0} )}{\ln(\frac{1}{2} )}$

Given information:

$A=0.25A_0\\h=5715\text{ yrs}$

Plug in given values and solve for t.

$t=\frac{5715 *\ln(0.25) }{\ln(\frac{1}{2} )} =11430 \text{ yrs}$

With correct significant figures, this would be 11000 years.

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3 years ago

cross contamination can it be caused by carrying either drinking glasses by the rims,a plate by its underside surface, utensils

harkovskaia [24]

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Cross contamination refers to the transfer of harmful microbes to foods from various sources. The rim of a drinking glass is where you put your mouth when you are drinking from a glass cup. If one is carrying a drinking glass by the rim, one can easily transfer the dirty in one's hand to the glass and this will be ingested by person who use the cup. Drinking glasses should be carried by holding their bases.

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3 years ago

Read 2 more answers

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Answer:

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Explanation:

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3 years ago

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ladessa [460]