What might be a scientific question

How many moles are in 2.98x10^23 particles?

Novosadov [1.4K]

Answer:

$\boxed {\boxed {\sf 0.495 \ mol}}$

Explanation:

We are given a number of particles and asked to convert to moles.

<h3>1. Convert Particles to Moles </h3>

1 mole of any substance contains the same number of particles (atoms, molecules, formula units) : 6.022 *10²³ or Avogadro's Number. For this question, the particles are not specified.

So, we know that 1 mole of this substance contains 6.022 *10²³ particles. Let's set up a ratio.

$\frac { 1 \ mol }{6.022*10^{23 } \ particles}}$

We are converting 2.98*10²³ particles to moles, so we multiply the ratio by that value.

$2.98*10^{23} \ particles *\frac { 1 \ mol }{6.022*10^{23 } \ particles}}$

The units of particles cancel.

$2.98*10^{23} *\frac { 1 \ mol }{6.022*10^{23 } }}$

$\frac { 2.98*10^{23}}{6.022*10^{23 } }} \ mol$

$0.4948522086 \ mol$

<h3>2. Round</h3>

The original measurement of particles (2.98*10²³) has 3 significant figures, so our answer must have the same.

For the number we found, 3 sig figs is the thousandth place.

The 8 in the ten-thousandth place (0.4948522086) tells us to round the 4 up to a 5 in the thousandth place.

$0.495 \ mol$

2.98*10²³ particles are equal to approximately <u>0.495 moles.</u>

3 0

3 years ago

Calculate the DH°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. DH°f means delta or change

USPshnik [31]

Answer: +178.3 kJ

Explanation:

The chemical equation follows:

$CaCO_3(s)\rightarrow CaO(s)+CO_2(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(CaO(s))})+(1\times \Delta H^0f_{CO_2}]-[(1\times \Delta H^o_f_{(CaCO_3(s))})]$

We are given:

$\Delta H^o_f_{(CaO(s))}=-635.1kJ/mol\\\Delta H^o_f_{(CaCO_3(s))}=-1206.9kJ/mol\\\Delta H^o_f_{(CO_2(g))}=-393.5kJ/mol\\\Delta H^o_{rxn}=?$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(1\times (-635.1))+(1\times (-393.5))]-[(1\times (-1206.9))]$

The DH°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide is +178.3 kJ

5 0

3 years ago

Help help help help help

Rina8888 [55]

Answer:

Temporary hardness is a type of water hardness caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). ... However, unlike the permanent hardness caused by sulfate and chloride compounds, this "temporary" hardness can be reduced by boiling the water.

5 0

3 years ago

B. For the following questions, use the reaction NO2(g) N2(g) + O2(g), with ΔH = –33.1 kJ/mol and ΔS= 63.02 J/(mol·K).

Troyanec [42]

Answer:

I. Kindly, see the attached image.

II. The reaction is exothermic.

III. - 51.88 kJ/mol.

IV. The reaction is spontaneous.

Explanation:

I. Draw a possible potential energy diagram of the reaction. Label the enthalpy of the reaction.

Since the sign of ΔH is negative, the reaction is exothermic reaction.

In an exothermic reaction, the energy of the reactants is higher than that of the products.

<u><em>Kindly see the attached image to show you the potential energy diagram of the reaction.</em></u>

<em>II. Is the reaction endothermic or exothermic? Explain your answer.</em>

The reaction is exothermic reaction.

The sign of ΔH indicates wither the reaction is endothermic or exothermic one:

If the sign is positive, the reaction is endothermic.

If the sign is negative, the reaction is exothermic.

Herein, <em>ΔH = - 33.1 kJ/mol, </em>so the reaction is exothermic.

<em>III. What is the Gibbs free energy of the reaction at 25°C? </em>

∵ ΔG = ΔH - TΔS.

Where, ΔG is the Gibbs free energy change (J/mol).

ΔH is the enthalpy change (ΔH = - 33.1 kJ/mol).

T is the temperature (T = 25°C + 273 = 298 K).

ΔS is the entorpy change (ΔS = 63.02 J/mol.K = 0.06302 J/mol.K).

IV. Is the reaction spontaneous or nonspontaneous at 25°C?

The sign of ΔG indicates the spontaneity of the reaction:

If ΔG < 0, the reaction is spontaneous.

If ΔG = 0, the reaction is at equilibrium.

If ΔG > 0, the reaction is nonspontaneous.

Herein, <em>ΔG = - 51.88 kJ/mol, </em>so the reaction is spontaneous.

7 0

3 years ago

if 10 moles of A and 7.5 moles of B are taken in a flask, identify the value of moles of A4B3 produced in a reaction.

natta225 [31]

The number of moles of A4B3 produced in a reaction is obtained by stoichiometry.

The term stoichiometry refers to mass-mole relationship. The first step in solving this problem is by writing the correct reaction equation as follows;

4A + 3B -------> A4B3

If 4 moles of A yields 1 mole of A4B3

10 moles of A yields 10 * 1/4 = 2.5 moles of A4B3

Therefore, 2.5 moles of A4B3 is produced.

Learn more: brainly.com/question/9743981

3 0

3 years ago