If you have exactly 2.00 moles each, of two different substances, then which of the following must be true about the two samples? They have the same mass. They have the same weight. They have the same number of particles. Both b and c.

Given:

C= 58.8% ,

H= 9.8% ,

and O=31.4 %

molar mass is = 102 g/mol.

empirical formula=

58.8/C(12.01)= 4.9

9.8/H(1.01)= 9.7

31.4/O(15.99)= 1.96

divide it by the least value so it is 1.96 which shows,

4.9/1.96= 2.5

9.7/1.96= 5

(C2.5H₅O)₂= C₅H₁₀O₂

molecular formula= C₁₀H₂₀O₄

It would a a chemical change as you cant see the boiling points changing or being formed. Physical changes are only when you visibly and physically observe the change

Answer : The correct option is, (C)the number of molecules

Explanation :

When we are comparing 1 mole of oxygen gas [tex](O_2)[/tex] with 1 mole of carbon monoxide gas [tex](CO)[/tex] then we conclude that,

In 1 mole of oxygen gas [tex](O_2)[/tex], there are two number of molecules of oxygen.

In 1 mole of carbon monoxide gas [tex](CO)[/tex], there are two number of molecules (carbon and oxygen).

Hence, the number of molecules must be the same when comparing 1 mole of oxygen gas, with 1 mole of carbon monoxide gas.

Answer:

-∆G and +Eocell

Explanation:

For an electrochemical reaction to be spontaneous, the change in free energy must be negative. This applies to all chemical reactions as a basic condition for spontaneity of chemical reactions.

More particular to an electrochemical cell is the value of the standard cell voltage. A positive value of standard cell voltage implies a spontaneous electrochemical reaction.

The relative atomic mass of copper on a newly discovered planet is [tex]\boxed{63.54{\text{ amu}}}[/tex] .

Further explanation:

An atom is also written as [tex]_{\text{Z}}^{\text{A}}{\text{X}}[/tex] , where A is the atomic mass or mass number, Z is the atomic number, and X is the letter symbol of the element.

Isotopes:

Atoms of the same element with same value of atomic number but different value of mass numbers are called isotopes. Isotopes generally have the same number of protons but the number of neutrons is different.

[tex]_{\mathbf{6}}^{{\mathbf{11}}}{\mathbf{C}}[/tex]  and [tex]_{\mathbf{6}}^{{\mathbf{12}}}{\mathbf{C}}[/tex]  are examples of isotopes. Both are the atoms of the same element carbon. The mass number of [tex]_{\mathbf{6}}^{{\mathbf{11}}}{\mathbf{C}}[/tex]  is 11 while that of  [tex]_{\mathbf{6}}^{{\mathbf{12}}}{\mathbf{C}}[/tex] is 12. But both of these have the same atomic number, i.e, 6.

Relative Atomic Mass:

It is defined as the average mass of an atom of the element compared to 1/12th of the mass of carbon-12 atom. It is represented by [tex]{{\text{A}}_{\text{r}}}[/tex] . The formula to calculate the relative atomic mass of an element is as follows:

[tex]{{\text{A}}_{\text{r}}} = \frac{{\sum {\left\{{\left({{\text{Relative isotopic mass}}}\right)\left({{\text{\%  abundance}}}\right)}\right\}}}}{{100}}[/tex]

Here,

[tex]{{\text{A}}_{\text{r}}}[/tex]  is the relative atomic mass.

It is given that copper (Cu) exists in two isotopic forms, one is 63 Cu, and the other is 65 Cu. So the relative atomic mass of Cu is calculated as follows:

[tex]{{\text{A}}_{\text{r}}}{\text{ of Cu}}=\frac{{\left[\begin{gathered}\left({{\text{Mass of 63 Cu}}}\right)\left({{\text{\%  abundance of 63 Cu}}}\right)+\hfill\\\left({{\text{Mass of 65 Cu}}}\right)\left({{\text{\%  abundance of 65 Cu}}}\right)\hfill\\\end{gathered}\right]}}{{100}}[/tex]                       …… (1)

The mass of 63 Cu is 62.9300 amu.

The percentage abundance of 63 Cu is 69.15 %.

The mass of 65 Cu is 64.9200 amu.

The percentage abundance of 65 Cu is 30.85 %.

Substitute these values in equation (1).

[tex]\begin{aligned}{{\text{A}}_{\text{r}}}{\text{ of Cu}}&=\frac{{\left[{\left( {{\text{62}}{\text{.9300 amu}}}\right)\left({{\text{69}}{\text{.15}}}\right)+\left({{\text{64}}{\text{.9200 amu}}}\right)\left({{\text{30}}{\text{.85}}}\right)}\right]}}{{100}}\\&=\frac{{{\text{4351}}{\text{.6095 amu}}+{\text{2002}}{\text{.782 amu}}}}{{100}}\\&={\text{63}}{\text{.543915 amu}}\\&\approx{\text{63}}{\text{.54 amu}}\\\end{aligned}[/tex]

So the relative atomic mass of copper on a newly discovered planet is 63.54 amu.

Learn more:

1. Calculate the moles of chlorine in 8 moles of carbon tetrachloride: https://brainly.com/question/3064603

2. Calculate the moles of ions in the solution: https://brainly.com/question/5950133

Answer details:

Grade: Middle School

Subject: Chemistry

Chapter: Mole Concept  

Keywords: percentage abundance, 63 Cu, 65 Cu, 62.9300 amu, 64.9200 amu, 30.85 %, 69.15 %, 63.54 amu, copper, isotopes, carbon-12, Ar, Cu.

This problem requires using the concept of pH and pOH. The “p” stands for the negative log so pH and pOH represent the negative log of the concentration of hydrogen or hydroxide ions.

Here is the solution:

pOH = -log [OH-]

pOH = -log [1.83x10^-7 M]

pOH = 6.74

pH + pOH = 14

pH = 14 - 6.74

pH = 7.26

pH = -log [H3O+]

7.26 = -log[H3O+]

[H3O+] = 5.46 x 10^-8 M

The heat of reaction for the combustion of a mole of titanium in the given calorimeter setup is approximately 14765.89 kJ/mol, as determined by calculating the total heat absorbed using the calorimeter's heat capacity and the mass and molar mass of titanium.

When 1.640 g of titanium is combusted in a bomb calorimeter, the resulting temperature increase from 25.00 °C to 76.50 °C can be used to calculate the heat of reaction for the combustion of a mole of titanium. Given that the heat capacity of the calorimeter is 9.84 kJ/°C, we can determine the total heat absorbed by the calorimeter during the reaction.

First, we calculate the total heat absorbed (q) by multiplying the heat capacity (C) by the change in temperature (ΔT):
q = C × ΔT
q = 9.84 kJ/°C × (76.50 °C - 25.00 °C)
q = 9.84 kJ/°C × 51.50 °C
q = 506.34 kJ

Next, to find the heat of reaction per mole of titanium, we convert the mass of titanium to moles using its molar mass (47.87 g/mol):
Number of moles = mass / molar mass
Number of moles = 1.640 g / 47.87 g/mol
Number of moles ≈ 0.0343 mol

Now, we can determine the heat of reaction per mole:
Heat of reaction per mole = q / Number of moles
Heat of reaction per mole ≈ 506.34 kJ / 0.0343 mol
Heat of reaction per mole ≈ 14765.89 kJ/mol

The heat of reaction for the combustion of a mole of Ti in this calorimeter is approximately 14765.89 kJ/mol.

Final answer:

The volume of gas produced by two antacid tablets is correctly identified as 400 cm3, making option A correct. For the moles of oxygen inhaled under given conditions, 1.21 moles, option B, is also correctly identified using the ideal gas law.

Explanation:

Chemistry Problem Solutions

The first question deals with the stoichiometry of a reaction between vinegar and antacid tablets, specifically focusing on the volume of gas produced in reaction to the quantity of antacid tablets used. Given that three tablets produce 600 cm3 of gas and assuming the reaction proceeds in a linear fashion (due to being the limiting reagent), the volume of gas produced by two tablets would indeed be 400 cm3 which is option A. Hence, your answer to the first question is correct.

For the second question about calculating moles of oxygen inhaled, we use the ideal gas law formula, PV=nRT, where P is the pressure (converted to atm), V is the volume in liters, n is the moles of gas, R is the universal gas constant (0.0821 L·atm·K-1·mol-1), and T is the temperature in Kelvin. By plugging in the values (and converting 1000 kPa to approximately 9.869 atm), we find that the moles of oxygen inhaled are roughly 1.21 moles, and so your answer B is also correct.

Answer:

a) 5.40 g B : [tex]3.012\times 10^{23}[/tex] atoms

b) 0.250 mol K : [tex]1.51\times 10^{23}[/tex] atoms

c) 0.0384 mol K : [tex]0.23\times 10^{23}[/tex] atoms

d) 0.02550 g Pt: [tex]7.8\times 10^{19}[/tex] atoms

e)  [tex]1.00\times 10^-{10} g[/tex] Au: [tex]0.03\times 10^{13}[/tex] atoms

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}[/tex]

a) 5.40 g B

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{5.40g}{11g/mol}=0.5moles[/tex]

1 mole of boron contains = [tex]6.023\times 10^{23}[/tex] atoms

Thus 0.5 moles  of boron contain =[tex]\frac{6.023\times 10^{23}}{1}\times 0.5=3.012\times 10^{23}[/tex] atoms

b) 0.250 mol K

1 mole of potassium (K) contains = [tex]6.023\times 10^{23}[/tex] atoms

Thus 0.250 moles of potassium contain =[tex]\frac{6.023\times 10^{23}}{1}\times 0.250=1.51\times 10^{23}[/tex] atoms

c) 0.0384 mol K

1 mole of potassium (K) contains = [tex]6.023\times 10^{23}[/tex] atoms

Thus 0.0384 moles of potassium (K) contain =[tex]\frac{6.023\times 10^{23}}{1}\times 0.0384=0.23\times 10^{23}[/tex] atoms

d) 0.02550 g Pt

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{0.02550 g}{195g/mol}=1.3\times 10^{-4}moles[/tex]

1 mole of platinum contains = [tex]6.023\times 10^{23}[/tex] atoms

Thus [tex]1.3\times 10^{-4}moles[/tex] of platinum contain=[tex]\frac{6.023\times 10^{23}}{1}\times 1.3\times 10^{-4}=7.8\times 10^{19}[/tex] atoms

e) [tex]1.00\times 10^-{10}g[/tex] Au,

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{1.00\times 10^{-10}g}{197g/mol}=0.005\times 10^{-10}moles[/tex]

1 mole of gold contains = [tex]6.023\times 10^{23}[/tex] atoms

Thus [tex]0.005\times 10^{-10}moles[/tex] of platinum contain=[tex]\frac{6.023\times 10^{23}}{1}\times 0.005\times 10^{-10}=0.03\times 10^{13}[/tex] atoms

The partial pressure of oxygen when the atmospheric pressure is 770 mm Hg and oxygen represents 13% of the total is 100.1 mm Hg. Since the choices don't include decimals, the closest answer and the correct one would be 100 mm Hg.

If the atmospheric pressure is 770 mm Hg and oxygen represents 13% of the total, then the partial pressure of oxygen is calculated by multiplying the total atmospheric pressure by the percentage of oxygen present. So, the partial pressure of oxygen (Po₂) can be found using the formula:

Po₂ = Total atmospheric pressure x (percent content in mixture)

In this case:

Po₂ = 770 mm Hg x 0.13 = 100.1 mm Hg

Since the values provided in the question for the partial pressure of oxygen don't include decimals, the most appropriate answer is 100 mm Hg, which is the value closest to our calculated result.

Increase along the Gulf Coast and climate change at sea level. Warming ocean waters expand as temperatures rise, while mountain glaciers and inland ice melt.

Climate is a region's averaged long-term weather pattern over a period of time, usually 30 years. More precisely, it is the average and variation of climatic variables over a period of time that can range from a few months to many millions of years.

The average of the weather is the climate. As an illustration, you can anticipate snow in the Northeast in January or hot and muggy weather in the Southeast in July. Climate is this.

Nearly every element of our life is impacted by the climate, including our food supplies, transportation systems, clothing choices, and vacation destinations. It significantly affects our future, our health, and our means of subsistence. The long-term pattern of the weather in any given location is called the climate.

Thus, increase along the Gulf Coast and climate change at sea level.

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The Gulf Coast and similar regions are experiencing land loss due to sea level rise resulting from melting glaciers and ice sheets.

The loss of land area on the Gulf Coast as oceans expand is primarily a result of sea level rise and coastal erosion. As glaciers and ice sheets melt, including those in Greenland and West Antarctica, sea levels rise at an approximate rate of 3 millimeters per year, contributing to land loss along coastlines. The problem is exacerbated along the Atlantic coast by factors such as low elevations and subsiding land. The coastline from Florida to New York, for example, lost more land than it gained between 1996 and 2011, indicating a negative net change in land area.

Moreover, global assessments reveal that roughly 70% of the world's sandy shorelines are retreating, with a significant proportion of beaches eroding at rates that exceed 0.5 meters per year. Specifically, for every 361 gigatonnes per year of ice mass melting into the ocean, sea levels rise by approximately 1 millimeter. Glaciologists project that if current trends continue, we could see more than 1 meter of sea level rise by 2100, considering both melting land ice and thermal expansion of the ocean water.

The empirical formula for the compound decomposed in the laboratory which resulted in 1.78 g of Nitrogen and 4.05 g of Oxygen can be calculated by finding the moles of each element and comparing ratios. Based on the calculation, the empirical formula for the compound is NO2.

First, we determine the number of moles of each element involved in the compound. Recall the atomic weight of Nitrogen (N) is about 14 g/mol and Oxygen (O) is about 16 g/mol.

The given weight of Nitrogen is 1.78 g. So, divide this by the atomic weight to get the number of moles: 1.78 g N / 14 g/mol = 0.127 moles of Nitrogen. Similarly for Oxygen, we have 4.05 g so: 4.05 g O / 16 g/mol = 0.253 moles of Oxygen.

To find the empirical formula, we divide each of these by the smallest number of moles, which is for Nitrogen: 0.127/0.127 = 1 for Nitrogen, and 0.253/0.127 = 2 for Oxygen. Hence, the empirical formula for the compound is N1O2 or simply NO2.

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The empirical formula of the compound is N1O2.

To determine the empirical formula of the compound, we need to find the ratio of nitrogen to oxygen. The given data states that 1.78 g of nitrogen and 4.05 g of oxygen were produced. First, convert the mass of each element to moles using their molar masses. The molar mass of nitrogen is 14 g/mol, so 1.78 g of nitrogen is equal to 0.127 moles. The molar mass of oxygen is 16 g/mol, so 4.05 g of oxygen is equal to 0.253 moles. Next, divide each mole value by the smallest mole value to get the mole ratio. In this case, the ratio is approximately 1:2. Therefore, the empirical formula of the compound is N1O2.

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Answer:

∆hf0 of products minus ∆hf0 of reactants

Explanation: