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3 years ago

15

But volcanoes are not all bad. Can you assess the value of volcanoes for the Earth? Why are they necessary and what good do they

do?

1 answer:

Gelneren [198K]3 years ago

8 0

Answer:

yes

Explanation:

volcanoes have done wonderful things for the earth

They help cool off the earth removing heat from its interior
volcanic emissions have produced the atmosphere and the water of the oceans
volcanoes make islands and add to the continent

volcanoes are necessary because:

fertile is another advantage of volcanic activity."In places like Japan,Indonesia,Philippines,Hawaii,volcanic material mixed in with the soil provides a lot of important nutrients

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_Li + __F2 → _LIF<br> How do I balance this?

Semmy [17]

Answer:

2Li + F₂ → 2LiF

Explanation:

The reaction expression is given as:

Li + F₂ → LiF

We are to balance the expression. In that case, the number of atoms on both sides of the expression must be the same.

Let use a mathematical approach to solve this problem;

Assign variables a,b and c as the coefficients that will balance the expression:

aLi + bF₂ → cLiF

Conserving Li: a = c

F: 2b = c

let a = 1, c = 1 and b = $\frac{1}{2}$

Multiply through by 2;

a = 2, b = 1 and c = 2

2Li + F₂ → 2LiF

5 0

3 years ago

What is the limiting reagent when a 2.00 g sample of ammonia is mixed with 4.00 g of oxygen?

UNO [17]

Answer:

Ammonia is limiting reactant

Amount of oxygen left = 0.035 mol

Explanation:

Masa of ammonia = 2.00 g

Mass of oxygen = 4.00 g

Which is limiting reactant = ?

Balance chemical equation:

4NH₃ + 3O₂ → 2N₂ + 6H₂O

Number of moles of ammonia:

Number of moles = mass/molar mass

Number of moles = 2.00 g/ 17 g/mol

Number of moles = 0.12 mol

Number of moles of oxygen:

Number of moles = mass/molar mass

Number of moles = 4.00 g/ 32 g/mol

Number of moles = 0.125 mol

Now we will compare the moles of ammonia and oxygen with water and nitrogen.

NH₃ : N₂

4 : 2

0.12 : 2/4×0.12 = 0.06

NH₃ : H₂O

4 : 6

0.12 : 6/4×0.12 = 0.18

O₂ : N₂

3 : 2

0.125 : 2/3×0.125 = 0.08

O₂ : H₂O

3 : 6

0.125 : 6/3×0.125 = 0.25

The number of moles of water and nitrogen formed by ammonia are less thus ammonia will be limiting reactant.

Amount of oxygen left:

NH₃ : O₂

4 : 3

0.12 : 3/4×0.12= 0.09

Amount of oxygen react = 0.09 mol

Amount of oxygen left = 0.125 - 0.09 = 0.035 mol

3 0

3 years ago

For the reaction shown, calculate how many moles of NO2 form when each amount of reactant completely reacts.

Anton [14]

Answer:- 2.4 mol $NO_2$ .

Solution:- It asks to calculate the moles of $NO_2$ formed when 1.2 moles of $N_2O_5$ are reacted.

There is 2:4 mol ratio between $N_2O_5$ and $NO_2$ . So, the moles of reactant are multiplied by the mol ratio to get the moles of $NO_2$ . The calculations are shown below:

$1.2mol N_2O_5(\frac{4mol NO_2}{2mol N_2O_5})$

= 2.4 mol $NO_2$

So, 2.4 moles of $NO_2$ are formed when 1.2 moles of $N_2O_5$ were reacted.

7 0

3 years ago

Read 2 more answers

Different kinds of wood have different densities. The density of american white oak wood is generally 0.77 g/cm3. If Jim grabs a

mixas84 [53]

Answer:

m= 29.645 g

Explanation:

Density:

Density is equal to the mass of substance divided by its volume.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Symbol:

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Given data:

density of wood = 0.77 g/cm³

volume= 38.5 cm³

mass= ?

Solution:

d= m/v

m= d × v

m= 0.77 g/cm³× 38.5 cm³

m= 29.645 g

7 0

3 years ago

Dissolve 30 g of sodium sulphate into 300 mL of water

Aneli [31]

Answer:

number of moles = 0.21120811

Explanation:

To find the number of moles, given the mass of the solute, we use the formula:

$\mathrm{n = \dfrac{ m }{ M } }$

$\mathrm{n = number\:of\:moles\:(mol)}$

$\mathrm{m = mass\:of\:solute\:(g)}$

$\mathrm{M = molar\:mass\:of\:solute\:( \dfrac{ g }{ mol } )}$

Label the variables with the numbers in the problem:

$\mathrm{n =\:?}$

$\mathrm{m =30\:g }$

$\mathrm{M =\:?\:Calculate\:the\:molar\:mass }$

The first thing we have to do is find the molar mass of sodium sulfate, in order for us to use the formula for finding the number of moles:

Formula for finding the molar mass of sodium sulfate:

$M({ \left Na \right }_{ 2 } { \left So \right }_{ 4 }) = m \left( Na \right) +m \left( S \right) +m \left( O \right)$

For the variables and what they mean are below for finding the molar mass of sodium sulfate:

$\mathrm{M =molar\:mass }$

$\mathrm{m =moles=2\:moles\:for\:Na\:,1\:mole\:for\:S,\:and\:4\:moles\:for\:O}$

$\mathrm{Na =sodium=22.99\:g }$

$\mathrm{S =sulfur=32.06\:g }$

$\mathrm{O =oxygen=16.00\:g }$

Plug the numbers into the formula, to find the molar mass of sodium sulfate:

$M({ \left Na \right }_{ 2 } { \left So \right }_{ 4 }) = m \left( Na \right) +m \left( S \right) +m \left( O \right)$

$\mathrm{Substitute\:the\:values\:into\:the\:formula}$

$M = 2 \left( 22.99 \right) +1 \left( 32.06 \right) +4 \left( 16.00 \right)$

$\mathrm{Multiply\:2\:by\:22.99\:to\:get\:45.98\:and\:1\:by\:32.06\:to\:get\:32.06}$

$\mathrm{M = 45.98+32.06+4\:(16)}$

$\mathrm{Multiply\:4\:by\:16\:to\:get\:64}$

$\mathrm{M = 45.98+32.06+64}$

$\mathrm{Add\:45.98\:and\:32.06\:to\:get\:78.04}$

$\mathrm{M = 78.04+64}$

$\mathrm{Add\:78.04\:and\:64\:to\:get\:142.04}$

$\mathrm{M = 142.04}$

Now that we have found the molar mass, we can calculate the number of moles in the solution of sodium sulfate with the formula:

$\mathrm{n = \dfrac{ m }{ M } }$

$\mathrm{n =\:?}$

$\mathrm{m =30\:g }$

$\mathrm{M = 142.04\:g/mol}$

$\mathrm{Substitute\:the\:values\:into\:the\:formula}$

$\mathrm{n = \dfrac{ 30 }{ 142.04 }}$

$\mathrm{Divide\:142.04\:by\:30\:to\:get\:0.21120811}$

$\mathrm{n = 0.21120811}$

0.21120811 rounded gives you 0.2112

or if you did the problem without decimals

30 grams of sodium sulfate divided by its molecular weight – which we found to be 142 – gives us a value of 0.2113 moles.

3 0

2 years ago