How many moles of sodium chloride (NaCl) solute are in 155 grams of an 88.5 percent by mass solution?

Answer:

The correct answer, the charge of Cesium is +1

Explanation:

Hi!

Let's solve this!

The compound is: Cs2O.

We know that the oxygen valence number is -2.

We also know that the compound has to be balanced, so to balance the charges we need +2. As there are two Cs, we perform the following operation:

2 * (+ 1) -2 = + 2-2 = 0

We conclude that the correct answer, the charge of Cesium is +1

Answer: 1. Chemical energy

2. Mechanical energy

Explanation:

The law of conservation of energy states that energy changes from one form of energy to another but it is neither created nor destroyed.

The fuel consists of chemical energy which when burn results in the release of energy in the form of heat or thermal energy. The heat energy is converted into mechanical energy by the internal machinery of the automobile engine. This mechanical energy is used to run the automobile.

Both technological design and scientific investigation involve making observations, identifying questions, researching, formulating hypotheses, and testing them.

The steps that are always part of both the process of technological design and the process of scientific investigation include: making observations, identifying a question to be answered, conducting research on existing knowledge, forming a hypothesis, and then testing that hypothesis.

It is important in both processes to document each step, provide justification for decisions, and communicate the results clearly. In doing so, the science connection behind each choice and the justification for the selected solution, based on factors and weights of requirements and constraints, should be well articulated.

Answer:

the rotation of the globe

Explanation:

As mentioned the model is representing the day and night cycle of earth thus the lamp must be the sun and the globe is earth.

The earth completes one year in taking one complete revolution around the sun (globe revolve around lamp).Thus due to revolution of earth the year gets completed.

The day and night of earth is due to rotation of earth on its own axis. The earth took 24 hours to complete one rotation on its axis.

Thus the rotation of globe causes it to receive light at different times.

Answer:

true

Explanation:

because i said so

The combustion of 43.9 g of ammonia produces 118.6 g of NO2.

To determine the mass of NO2 produced from the combustion of 43.9 g of ammonia, we first need to calculate the moles of ammonia used. The molar mass of ammonia (NH3) is 17.03 g/mol. We can use the molar ratio from the balanced equation to find the moles of NO2 produced.

4NH3 (g) + 7O2 (g) → 4NO2 (g) + 6H2O (g)

From the balanced equation, the molar ratio between NH3 and NO2 is 4:4. Therefore, the moles of NO2 produced is also equal to the moles of NH3 used. Finally, we can calculate the mass of NO2 produced by multiplying the moles of NH3 used by the molar mass of NO2 (46.01 g/mol).

Mass of NO2 produced = Moles of NH3 used × Molar mass of NO2

Now let's plug in the numbers:

Mass of NO2 produced = 43.9 g × (46.01 g/mol / 17.03 g/mol) = 118.6 g

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The correct answer is; "The nucleus has a positive charge and is surrounded by negatively charged electrons"

The atom is composed of three particles, electrons, protons and neutrons.

The electrons are negatively charged, protons are positively charged while neutrons have no charge.

The protons and neutrons are housed in the nucleus of the atom. Since the protons are positively charged, the nucleus is regarded as being positively charged.

The nucleus is surrounded by negatively charged electrons.

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The mole of oxygen needed to react with 6 moles of ethane is 1.16 mol.

Combustion reactions are those in which the substance react with oxygen and produce heat and light.

The reaction will be

[tex]\rm 2C_2H_6 + 7O_2 = 4CO_2 + 6H_2O[/tex]

Now,

[tex]1\; mole\;of \;ethane \times \dfrac{7\;mol\;ofO_2}{6\;mol\;of\;C_2H_6} = 1.16 mol[/tex]

Thus, the moles of oxygen is 1.16 mol.

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Final answer:

To react with 6 moles of ethane, 21 moles of oxygen would be needed.

Explanation:

To determine the number of moles of oxygen needed to react with 6 moles of ethane, we need to use the balanced chemical equation for the reaction. The balanced equation for the combustion of ethane is:

C2H6 + 3.5O2 → 2CO2 + 3H2O

From the balanced equation, we can see that 1 mole of ethane reacts with 3.5 moles of oxygen. Therefore, 6 moles of ethane would require:

(6 moles ethane) * (3.5 moles O2 / 1 mole ethane) = 21 moles of oxygen

Hydrogen bonds are approximately 5% of the bond strength of covalent bonds, for example (C-C or C-H bonds).
Hydrogen bonds strength in water is approximately 20 kJ/mol, strenght of carbon-carbon bond is approximately 350 kJ/mol and strengh of carbon-hydrogen bond is approximately 340 kJ/mol.
20 kJ/350 kJ = 0,057 = 5,7 %.

Final answer:

The strength of a hydrogen bond is approximately 5% that of a covalent bond. The correct answer is c. 5%.

Explanation:

The average strength of a hydrogen bond is approximately 5% of the average strength of a covalent bond. Therefore, the correct answer to the question is c. 5%. Hydrogen bonds are a type of intermolecular attractive force where a hydrogen atom covalently bonded to an electronegative atom is attracted to a lone pair of electrons on a neighboring molecule. While hydrogen bonds are much stronger than other dipole-dipole interactions, they are still significantly weaker than covalent bonds, but integral for holding together structures like DNA and proteins in biology.

Final answer:

To calculate the molarity of diluted aqueous solutions of HCl and KI, we apply the dilution formula M1V1 = M2V2, producing final molarities of 0.319 M for HCl and 1.37×10⁻² M for KI.

Explanation:

The question involves calculating the molarity of two different aqueous solutions after dilution. For both parts (a) and (b), we will apply the concept that molarity (M) is the number of moles of solute per liter of solution, and that the number of moles of solute remains constant during the dilution process, allowing us to use the equation M1V1 = M2V2, where M1 and V1 are the initial molarity and volume, respectively, and M2 and V2 are the final molarity and volume, respectively.

For the solution of HCl: Given an initial volume of 25.5 mL (or 0.0255 L) and molarity of 6.25 M, diluted to a final volume of 0.500 L, the final molarity (M2) can be calculated as follows:M2 = (M1 × V1) / V2 = (6.25 M × 0.0255 L) / 0.500 L = 0.319 M.

For the solution of KI: With an initial volume of 8.25 mL (or 0.00825 L) and molarity of 2.00×10⁻² M, diluted to a final volume of 12.0 mL (or 0.012 L), the final molarity is calculated similarly: M2 = (M1 × V1) / V2 = (2.00×10⁻² M × 0.00825 L) / 0.012 L = 1.37×10⁻² M.

Answer : The number of moles of carbon in the original sample were 0.166 moles.

Explanation :

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

[tex]C_xH_yO_z+O_2\rightarrow CO_2+H_2O[/tex]

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of [tex]CO_2=7.33g[/tex]

Mass of [tex]H_2O=3.00g[/tex]

We know that:

Molar mass of carbon dioxide = 44 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 7.33 g of carbon dioxide, [tex]\frac{12}{44}\times 7.33=1.99g[/tex] of carbon will be contained.

Now we have to calculate the moles of carbon.

Moles of Carbon =[tex]\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{1.99g}{12g/mole}=0.166moles[/tex]

Therefore, the number of moles of carbon in the original sample were 0.166 moles.

When 5.40 moles of ethane are burned in excess oxygen, 10.80 moles of carbon dioxide are produced.

The balanced chemical equation for the combustion of ethane (C₂H₆) in oxygen (O₂) is:

C₂H₆ + 7/2 O₂ -> 2 CO₂ + 3 H₂O

From the balanced equation, we can see that 1 mole of ethane (C₂H₆) produces 2 moles of carbon dioxide (CO₂) during combustion. This means that the mole ratio of ethane to carbon dioxide is 1:2.

Given that 5.40 moles of ethane are burned, we can use this mole ratio to calculate the moles of carbon dioxide produced:

5.40 moles of C₂H₆ x (2 moles of CO₂ / 1 mole of C₂H₆) = 10.80 moles of CO₂

So, when 5.40 moles of ethane are burned in excess oxygen, 10.80 moles of carbon dioxide are produced.

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its c just took test

Answer:

Backward direction

Explanation:

Exothermic reaction: It is that reaction in which heat is evolved during reaction.

We are given

[tex]H_2+Cl_2\rightleftharpoons 2HCl[/tex]

It is exothermic reaction.

We know that in exothermic reaction   when we increase the temperature then the equilibrium shift in backward direction and when we decrease the temperature then the equilibrium shift in forward direction.

Therefore, when we increasing the temperature then the equilibrium shift in backward direction.

Le chateliers principle is applicable only to reversible reaction not to the irreversible reaction . The equilibrium will shift to the left side of the reaction that is towards the reactant on increasing the amount of NH₄Cl .

According to  le chatelier's principle if any change in temperature, pressure or concentration of reactant is brought in the reaction that is in equilibrium then the the equilibrium will shift so as to tend to counteract the effect of the change.

The balanced reaction is

[tex]\rm NH_4OH(aq) \rightleftharpoons NH_4^+(aq) + OH^-(aq)[/tex]

If we add [tex]\rm NH_4Cl[/tex] to the reaction the number of ions of [tex]NH_4^+[/tex] increases in the product side and hence the reaction will counteract to change and equilibrium shift towards left.

Therefore, the equilibrium will shift to the left side of the reaction that is towards the reactant on increasing the amount of NH₄Cl.

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To find the number of hydrogen atoms in 7.30 moles of ethanol, multiply the number of moles of hydrogen per mole of ethanol (6) by the total moles of ethanol (7.30), resulting in 43.8 moles of hydrogen. Then, multiply by Avogadro's number to get approximately 2.64 × 1025 hydrogen atoms.

To calculate the number of hydrogen atoms in 7.30 moles of ethanol, we first need to understand the chemical composition of ethanol. The chemical formula for ethanol is C2H6O, which indicates that each mole of ethanol contains 2 moles of carbon (C), 6 moles of hydrogen (H), and 1 mole of oxygen (O). Therefore, in one mole of ethanol, there are 6 moles of hydrogen atoms.

To find the total number of hydrogen atoms in 7.30 moles of ethanol, we multiply the number of moles of hydrogen per mole of ethanol (6) by the number of moles of ethanol (7.30):

Number of hydrogen atoms = 6 moles H/mole C2H6O × 7.30 moles C2H6O

Number of hydrogen atoms = 43.8 moles of hydrogen atoms.

Since one mole contains Avogadro's number of atoms, which is approximately 6.022 × 1023 atoms per mole, we calculate the total number of hydrogen atoms as follows:

Number of hydrogen atoms = 43.8 moles H × 6.022 × 1023 atoms/mole

Number of hydrogen atoms = approximately 2.64 × 1025 hydrogen atoms.

The concentration of HI present at equilibrium is approximately 1.13 M.

To find the equilibrium concentration of HI in the reaction between hydrogen (H₂) and iodine (I₂) to form hydrogen iodide (HI), we can follow these steps:

The balanced chemical equation for the reaction is:

[tex]H_2(g) + I_2(g) \rightleftharpoons 2HI(g)[/tex]

The given equilibrium constant, K_c, for this reaction at a certain temperature is 53.3.

In this scenario, we have:

This means that the initial concentrations of H₂ and I₂ are:

[tex][H_2]_{initial} = \frac{0.500 \text{ moles}}{1.00 \text{ L}} = 0.500 ext{ M}[/tex]

[tex][I_2]_{initial} = \frac{0.500 \text{ moles}}{1.00 \text{ L}} = 0.500 ext{ M}[/tex]

Let’s denote the change in concentration of H₂ and I₂ at equilibrium as -x (since they will decrease) and the increase in concentration of HI as +2x (because 1 mole of each H₂ and I₂ produces 2 moles of HI). The changes can be summarized as:

[tex][H_2] = 0.500 - x[/tex]
[tex][I_2] = 0.500 - x[/tex]
[tex][HI] = 0 + 2x[/tex]

At equilibrium, we can express K_c:

[tex]K_c = \frac{[HI]^2}{[H_2][I_2]}[/tex]

Substituting the equilibrium concentrations into the expression:

[tex]53.3 = \frac{(2x)^2}{(0.500 - x)(0.500 - x)}[/tex]

This simplifies to:

[tex]53.3 = \frac{4x^2}{(0.500 - x)^2}[/tex]

Cross-multiplying gives:

[tex]53.3(0.500 - x)^2 = 4x^2[/tex]

Expanding the left side:

[tex]53.3(0.250 - x + x^2) = 4x^2[/tex]

This leads to:

[tex]13.325 - 53.3x + 53.3x^2 = 4x^2[/tex]

Combining terms yields:

[tex]49.3x^2 - 53.3x + 13.325 = 0[/tex]

To solve this quadratic equation, we apply the quadratic formula:
[tex]x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}[/tex]
Where:

Calculating the discriminant:
[tex]b^2 - 4ac = (-53.3)^2 - 4(49.3)(13.325)[/tex]
Let's calculate
[tex]= 2840.89 - 2631.89 = 209.00[/tex]

Now substituting back into the formula, we compute:
[tex]x = \frac{53.3 \pm \sqrt{209}}{2(49.3)}[/tex]
Finding the positive root:
[tex]x \approx 0.563 \text{ (taking only the positive root for concentration)}[/tex]

We can now calculate the final concentration of HI:
[tex][HI]_{eq} = 2x = 2(0.563) \approx 1.126 ext{ M}[/tex]

The compound with the formula NiSO₃ is called nickel(II) sulfite.

In chemical nomenclature, we use systematic naming rules to name chemical compounds based on their chemical formulas. The formula nickel(II) sulfite represents a compound that contains the elements nickel (Ni), sulfur (S), and oxygen (O).

To name this compound:

Identify the cation (positively charged ion) and the anion (negatively charged ion) in the formula. In this case, the cation is nickel (Ni²⁺) and the anion is the polyatomic ion sulfite (SO₃²⁻).

Use the name of cation followed by name of the anion. Since the nickel ion (Ni²⁺) has a fixed charge of +2, we use the Roman numeral "II" in parentheses after "nickel" to indicate its charge. The polyatomic ion sulfite (SO₃²⁻) consists of one sulfur atom and three oxygen atoms.

Putting it all together, we get the name "nickel(II) sulfite" for the compound with the formula NiSO₃.

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