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3 years ago

How is a mole ratio written?

1 answer:

3 0

A mole ratio is a conversion factor that relates the amounts in moles of any two substances in a chemical reaction. The numbers in a conversion factor come from the coefficients of the balanced chemical equation. The following six mole ratios can be written for the ammonia forming reaction above.

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What is the density of a board dimensions are 5.54 cm x 10.6 cm X 199 cm and whose mass is 28.6kg

exis [7]

Answer:

$d=2.44\ g/cm^3$

Explanation:

Given that,

The dimensions of the board is 5.54 cm x 10.6 cm X 199 cm.

The mass of the board is 28.6 kg.

Since, 1 kg = 1000 grams

28.6 kg = 28.6 × 1000 g = 28600 grams

Density = mass/volume

So,

$d=\dfrac{28600\ g}{(5.54\times 10.6\times 199)\ cm^3}\\\\d=2.44\ g/cm^3$

So, the density of a board is $2.44\ g/cm^3$ .

4 0

3 years ago

A brick has a mass of and the Earth has a mass of . Use this information to answer the questions below. Be sure your answers hav

weeeeeb [17]

The given question is incomplete. The complete question is:

A brick has a mass of 4.0 kg and the earth has a mass of $6.0\times 10^{27}g$ Use this information to answer the questions below. Be sure your answers have the correct number of significant digits. What is the mass of 1 mole of bricks? Round your answer to 2 significant digits. How many moles of bricks have a mass equal to the mass of the Earth? Round your answer to 2 significant digits.

Answer: The mass of 1 mole of bricks is $2.4\times 10^{27}g$

2.5 moles of bricks have a mass equal to the mass of the Earth

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to its molecular mass and contains avogadro's number $6.023\times 10^{23}$ of particles.

Mass of 1 brick = 4.0 kg = 4000 g (1kg=1000g)

Thus mass of 1 mole of brick or $6.023\times 10^{23}$ bricks will be = $\frac{4000g}{1}\times 6.023\times 10^{23}=2.4\times 10^{27}g$

The mass of 1 mole of bricks is $2.4\times 10^{27}g$

Now $2.4\times 10^{27}g$ will correspond to = 1 mole of bricks

$6.0\times 10^{27}g$ will correspond to = $\frac{1}{2.4\times 10^{27}}\times 6.0\times 10^{27}=2.5moles$

2.5 moles of bricks have a mass equal to the mass of the Earth

5 0

3 years ago

Changes in DNA are known as mutations and can be sometimes produce beneficial changes in population. A mutant form of the normal

soldier1979 [14.2K]

The dark colored moths are beneficial in a polluted area because they have a lesser chance of being eaten since they blend into the trees polluted with soot.

4 0

3 years ago

The oxidation of copper(I) oxide, Cu2O(s) , to copper(II) oxide, CuO(s) , is an exothermic process. 2Cu2O(s)+O2(g)⟶4CuO(s) The c

dem82 [27]

Answer:

The work is

$W = -0.369kJ$

The energy change of the reaction is $\Delta U _{rxn} = 43.839 kJ$

Explanation:

From the question we are told that

The chemical equation for this reaction is

$2 Cu_2 O + O_2_{(g)} ----> 4 CuO_{(s)}$

The mass of $Cu_2 O$ is $m = 42.60g$

The enthalpy $Cu_2 O$ is $\Delta H_{re} = -43.47 \ kJ$ this also the change in energy in terms of heat

The pressure at which it is oxidized is $P = 1\ bar$

The no of moles of $Cu_2 O$ used in this reaction is mathematically represented as

$n = \frac{mass \ of \ Cu_2 O}{Molar \ mass \ of \ Cu_2 O}$

The molar mass of $Cu_2 O$ is a constant with a value $M = 143.1 g/mol$

Now substituting values

$n = \frac{ 42.60}{143.1}$

$n = 0.29769 \ moles$

From the reaction we see that

Two mole of $Cu_2 O$ reacts with One mole of $O_2$ to give Four moles of $CuO_{(s)}$

This means that

One mole of $Cu_2 O$ reacts with 0.5 mole of $O_2$ to give two moles of $CuO_{(s)}$

it also implies that

$0.29769 \ mole$ of $Cu_2 O$ reacts with $0.5 * 0.29769$ moles of $O_2$ to give $2* 0.29769$ moles of $CuO_{(s)}$

$0.29769 \ mole$ of $Cu_2 O$ reacts with $0.149$ moles of $O_2$ to give $0.595$ moles of $CuO_{(s)}$

Now the number of moles of gaseous reactant is

$N_{O_2} = 0.149 \ moles$

The number of moles of gaseous product is

$N_p = 0 \ moles$

So the change in number of moles for gaseous compounds is mathematically evaluated as

$\Delta N = 0- 0.149 \ moles$

$\Delta N = - 0.149 \ moles$

Now the workdone for the compound $Cu_2 O$ is mathematically represented as

$W = \Delta N RT$

Where R is the gas constant with a value of $R = 8.314 J/mol \cdot K$

T is the temperature with a value $T = 25 + 273 = 298 K$

Substituting values

$W = -0.149 * 8.314 * (298)$

$W = -0.369kJ$

Generally the internal energy change of the reaction can be represented as

$\Delta U _{rxn} = \Delta H_{re} - W$

Substituting value

$\Delta U _{rxn} = -43.47 - (-0.369)$

$\Delta U _{rxn} = 43.839 kJ$

This is the internal energy change on the reaction for 42.60 g of $Cu_2 O$

3 0

3 years ago

H2(g) + I2(g) ↔2HI(g) + heat. If more I2 is added, in what direction will the equilibrium shift? Group of answer choices

uranmaximum [27]

Answer:

Towards the products, or to the right

Explanation:

There are no provided answer choices, but the answer should be to the right.

By Le Chatelier's principle, which basically can be summarized as "if you mess with chemistry, chemistry messes back", if more reactants are added, the equilibrium will shift to the right towards the products in order to make more products and counteract the increase in I₂.

7 0

3 years ago