Classify Matter as Elements or Compounds Question If something is a compound, it is also . Select the correct answer below O an element O a pure substance a mixture a single atom
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The information that will be the most useful to define a constraint for the device is option  D. the temperature at which a reaction becomes unsafe for people

The temperature at which a reaction becomes unsafe for people is the most important information to define a constraint for the device, as safety is a primary concern when designing any device for human use. If the reaction releases heat that exceeds a safe temperature, it could cause injury to the user, so it's essential to have a constraint in place to ensure that the reaction stays within safe limits.

Therefore, Other factors such as the average size of a person's foot, the boiling and freezing points of water, and the most popular color for similar products, while important for other aspects of the design, are not as critical for ensuring the safety of the device and its users.

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A chemist is designing a warming device for keeping a person's feet warm when they are outside during cold weather. The device will contain substances that undergo a chemical reaction and release heat.

Which information will be the most useful to define a constraint for the device?

A. the average size of a person's foot

B. the boiling and freezing points of water

C. the most popular color for similar products

D. the temperature at which a reaction becomes unsafe for people

The mass of urea (CH4N2O) needed to prepare 52.0g of a solution in water in which the mole fraction of urea is 7.71×10−2 is 13.62 g.

The term mole fraction represents the number of molecules of a particular component in a mixture divided by the total number of moles in the given mixture. It's a way of expressing the concentration of a solution.

The mass of water = 48.5 g

number of moles of water = 52.0 g/18g/mol

= 2.8 moles of water

mole fraction of urea = 7.71×10−2

but mole fraction = mole of substance/ total number of moles

Let the number of moles of urea be x

7.71 × 10−2 = x / 2.8 + x

7.71 × 10 − 2 (2.8 + x) = x

7.71 × 10 - 5.6 + 2x = x

x = 0.227 moles of urea

mass of urea in solution = number of mole × molar mass

= 0.227 moles × 60 g/mol

= 13.62 g of urea

Thus, the mass of urea (CH4N2O) needed to prepare 52.0g of a solution in water in which the mole fraction of urea is 7.71×10−2 is 13.62 g.

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It will going to release 129 MJ of heat.

Mass of gasoline = 1.0 g, Heat released = 11 kcal. Density of gasoline = 0.74 g/mL

Here, we are asked to calculate heat in megajoules, released when 1.0 gal of gasoline burns.

First, let’s find the volume of 1.0 gal gasoline in mL = 1.0 gal gasoline  = 3785.41 mL

Now, let’s find the mass of gasoline in g:

      Mass = Density  volume

                 = 0.74 g/mL  3785.41 m        = 2801.20 g.

Given, 1 g releases 11 kcal. Let’s find the heat released by 2800 g:

= 2801.20 g

=  30813.2 kcal

Now, let’s convert the heat in kcal to MJ:

       1 kcal = 0.004186 MJ

Therefore, heat in megajoules will be:   = 30813.2 kcal = 128.98 MJ

Therefore, It will going to release 129 MJ of heat.

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The mole fraction of a substance in a mixture is the ratio of the number of moles of that substance to the total number of moles of all substances in the mixture.

converting the masses of CO2 and O2 into moles:

CO2: 26.1 g ÷ 44.01 g/mol = 0.59 moles

O2: 36.6 g ÷ 32.00 g/mol = 1.14 moles

adding up the total number of moles:

0.59 moles + 1.14 moles = 1.73 moles

dividing the number of moles of O2 by the total number of moles:

1.14 moles ÷ 1.73 moles = 0.66 or 66%

So the mole fraction of O2 in this mixture is 0.66 or 66%.

In chemistry, a mixture is a concoction of two or more compounds, each of which maintains its unique chemical identity and properties. Physical separation of the components in a mixture is possible using techniques like distillation, evaporation, or filtering. The qualities of a mixture, as opposed to a chemical compound, rely on the ratios of the constituent parts. Mixtures include things like air, salt water, and gasoline.

A substance made up of two or more separate chemical compounds that are not chemically linked is referred to as a mixture. When two or more substances are physically combined, their identities are maintained, and the mixture takes the shape of solutions, suspensions, or colloids.

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The solution having the lowest freezing point is 0.015 M BaCl₂. The Van Hoff factor for this solution is 3 and have greater concentration here.

Freezing point of a solution is the temperature at which it converts from solid to  liquid. The freezing point of a substance is dependent on the bond type, temperature, pressure and presence of impurities if any.

The depression in freezing point by the addition of a non volatile solid is a colligative property. It is directly proportional to the molality of the solution. The Vant Hoff factor of the solution is the number of ions it can furnish.

Here, the number ions furnished by barium chloride and sodium carbonate are 3. All other solutions have one or 2 ions in solution. Here, the concentration of BaCl₂ is greater and it will lower in freezing point much than other solutions.

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In a chemical reaction involving the formation of an intermediate activated complex, the step from reactants to the activated complex must always be exothermic. Option A is correct.

This step is called the activation energy, and it represents the energy required to form the activated complex, which is a high-energy transition state between the reactants and the products. The formation of the activated complex is exothermic because the activated complex is higher in energy than the reactants and lower in energy than the products.

The energy difference between the reactants and the activated complex is the activation energy, which is usually overcome by heat, light, or some other form of energy. Once the activation energy has been supplied, the reaction proceeds to form the products, which are lower in energy than the activated complex.

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Answer:

Explanation:The compound copper(II) Iodide is a strong electrolyte. Write the reaction when copper(ll) Iodide is put into water: The compound iron(III) sulfate is a strong electrolyte. Write the reaction when Iron(III) sulfate is put into water: Write the net ionic equation for the precipitation of iron (III) sulfide from aqueous solution: Write the net ionic equation for the following molecular equation. HI is a strong electrolyte. HF is a weak electrolyte. KF(aq) + HI(aq) arrow KI(aq) + HF(aq) Use H^+ for the hydronium ion. Write the net ionic equation for the following molecular equation. Fe(s) + Pb(NO3)2(aq) arrow Fe(NO3)2(aq) + Pb(s)

If m_c = m_l, then there is equal amounts of copper and lead.

To determine the relative amounts of each type of bull3t (copper and lead), we need to know the mass and volume of each type of bull3t. Assuming that the copper and lead are pure, the mass of each bull3t can be calculated using its density and volume.

Let's say the volume of the copper bull3t is V_c and the volume of the lead bull3t is V_l. Then, the mass of the copper bullet can be calculated as follows:

m_c = ρ_c * V_c

where ρ_c is the density of copper (8.96 g/cm3).

Similarly, the mass of the lead bull3t can be calculated as follows:

m_l = ρ_l * V_l

where ρ_l is the density of lead (11.4 g/cm3).

To determine the relative amounts of each type of bull3t, we need to compare their masses. If m_c > m_l, then there is more copper than lead. If m_c < m_l, then there is more lead than copper. And if m_c = m_l, then there is equal amounts of copper and lead.

Note: The actual masses of the bull3ts will depend on their individual volumes, which are not specified in the question. The above calculation provides only a relative comparison of the masses of the two types of bull3ts.

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The metal oxidation state, dn electron count, and total valence electron count of the following complexes are: a. Fe(CO)6: Metal oxidation state = 0, dn electron count = 6, total valence electron count = 18.

What is metal oxidation state?

Metal oxidation state is the degree of oxidation of a metal atom in an ion or molecule. It is an integer assigned to an element to indicate the number of electrons gained or lost when an atom of the element forms a chemical bond. Oxidation states are typically represented using Roman numerals, where positive oxidation states indicate a net gain of electrons, while negative oxidation states indicate a net loss of electrons. Oxidation states are important in understanding chemical bonding and redox reactions.

b. [Co(en)2Cl2]: Metal oxidation state = 3, dn electron count = 2, total valence electron count = 16

c. (TiCP2Cl)2: Metal oxidation state = +4, dn electron count = 2, total valence electron count = 20

d. Rh(PPh3)3Cl: Metal oxidation state = +3, dn electron count = 3, total valence electron count = 24

e. [(MeCN)HgMe]: Metal oxidation state = +2, dn electron count = 4, total valence electron count = 16

f. OSo: Metal oxidation state = 0, dn electron count = 2, total valence electron count = 10

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The concentration of 0.90% aqueous sodium chloride can be expressed in molarity as follows:

0.90 g/mL of sodium chloride = 0.0090 g/mL × 1 mole / 58.44 g = 0.000155 M

Next, we can compare the osmotic pressure of each solution to normal saline:

A) 1.0 M aq: KCl is hypertonic compared to normal saline. The osmotic pressure of a solution is directly proportional to its concentration. Therefore, a 1.0 M solution of KCl has a higher concentration and higher osmotic pressure than normal saline, which makes it hypertonic.

B) 0.5 M aq: K2SO4 is hypotonic compared to normal saline. A 0.5 M solution of K2SO4 has a lower concentration and lower osmotic pressure than normal saline, which makes it hypotonic.

C) 4.3 M aq: NH4Cl is hypertonic compared to normal saline. A 4.3 M solution of NH4Cl has a higher concentration and higher osmotic pressure than normal saline, which makes it hypertonic.

D) 0.15 M aq: sugar is hypotonic compared to normal saline. A 0.15 M solution of sugar has a lower concentration and lower osmotic pressure than normal saline, which makes it hypotonic.

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The general chemical equation  for the reaction of a halogen with a metal is M+ X[tex]\rightarrow[/tex] MX₂.

Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.

A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .

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The equation that shows the formation of cobalt (III) ion from the neutral atom of cobalt is written as below:

[tex]\rm Cu \rightarrow Cu^{3+} + 3 e^{-}[/tex]

Oxidation is the process of reaction with oxygen or donation of electrons to form the higher oxidation state. When a neutral atom donates one electron to other atom, it gains positive charge. Thus oxidizes to one higher oxidation state.

Cobalt is a transition metal exhibiting variable oxidation states as other transition metals. The possible oxidation states of cobalt are  +1, +2 and +3.

When cobalt atom donates 3 electrons from its valence shell. It forms the ion Co³⁺. The reaction can be represented as written above. The number of electrons donated is written in the right of the arrow.

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compared to a metal with an ASTM grain size of 3, a material with a grain size number of 7 would have finer crystals and would be stronger.

The ASTM (American Society for Testing and Materials) grain size number is a measure of the average size of the grains in a metal. A lower number indicates a material with larger grains, while a higher number indicates smaller grains. The size of the grains affects the mechanical properties of the metal, such as strength, toughness, and ductility. In general, metals with finer grain sizes have better mechanical properties, such as increased strength and improved ductility. This is because smaller grains result in a more uniform microstructure and reduced defects, leading to improved mechanical performance. Therefore, a metal with an ASTM grain size of 7 would be expected to have finer crystals and to be stronger compared to a metal with an ASTM grain size of 3.

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All of the options listed are molecules. The correct answer is D.

A molecule is a combination of two or more atoms that are chemically bonded together. The bonding of atoms forms a new substance with its own unique properties, which are different from the properties of the individual atoms that make it up.

Water (H₂O) is a molecule made up of two hydrogen atoms and one oxygen atom.

Ozone (O₃) is a molecule made up of three oxygen atoms.

Glucose (C₆H₁₂O₆) is a molecule made up of six carbon atoms, twelve hydrogen atoms, and six oxygen atoms.

In summary, a molecule is a smallest particle of a substance that retains the chemical composition and properties of that substance, and all of the options listed (water, ozone, and glucose) are examples of molecules.

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Answer:

C) 5 to 3

Hope it helped; please mark brainliest, I put a lot of effort into my answers!

Two electron bond pairs combine to generate two O–F bond pairs. Two single electron pairs make up the O-atom. There are three lone electron pairs in each F atom. There are thus eight lone electron pair overall.

The negatively charged particles known as electrons revolve about the outside of the nucleus. For scientists, it can be challenging to monitor them because of how quickly they spin. The tiniest particles in an atom, you can put 2000 of them out of a proton, they are drawn to the positive ions of the protons.

The smallest elemental component of an atom, the electron has a negative charge. Quantity of protons.

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Answer:

Question 1 ; 2.15 atm

Question 2; 1.078 atm

Step by step explanation:

Question 1

We can use the Ideal Gas Law to calculate the pressure: PV = nRT, where P is the pressure, V is the volume, n is the number of moles of gas, R is the gas constant (8.31 J/mol·K), and T is the temperature in Kelvin.

Given the initial conditions:

V1 = 2.27 L, T1 = 285 K, and P1 = 1.10 atm

And the final conditions:

V2 = 1.36 L, T2 = 306 K

We can rearrange the Ideal Gas Law to solve for P2:

P2 = (nRT2) / V2 = (nRT1) / V1 * (V1 / V2) = (P1 * V1 * T2) / (T1 * V2) = (1.10 atm * 2.27 L * 306 K) / (285 K * 1.36 L) = 2.15 atm

Question 2

The total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases. So, after adding the third gas, the total pressure will become:

0.292 atm + 0.676 atm + 0.110 atm = 1.078 atm.

The half-life of the radioactive substance is approximately 2.06 hours.

The half-life of a radioactive substance is the amount of time required for half of the initial amount of the substance to decay. If the rate of decay is proportional to the amount of the substance present at time t, the half-life of the substance can be determined as follows:

Let t be the half-life of the substance, then after t hours, the amount of the substance present will be 100 mg × (1/2) = 50 mg.

At time 4 hours, the amount of the substance present is 100 mg × (1 - 3%) = 97 mg.

Since the rate of decay is proportional to the amount of substance present, the half-life can be calculated as follows: t = 4 hours × (50 mg / 97 mg) = 2.06 hours.

Therefore, the half-life of the radioactive substance is approximately 2.06 hours.

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Answer:

1.25 L of C2H4 is equal to:

1.25 L / 22.4 L/mol = 0.0558 moles

From the balanced chemical equation, we see that for every 1 mole of C2H4 that reacts, 2 moles of H2O are formed.

So, for 0.0558 moles of C2H4:

0.0558 moles * 2 moles H2O/mole C2H4 = 0.1116 moles of H2O

0.1116 moles * 22.4 L/mol = 2.51 L H2O (3 sig figs)

The acid ionization constant for the acid is 1.40 x 10^-10.

The acid ionization constant (Ka) can be calculated using the equation:

Ka = [H+][A-] / [HA]

where [H+] and [A-] are the concentrations of the hydrogen ion and the conjugate base, respectively, and [HA] is the concentration of the undissociated acid.

Given that the percent dissociation is 0.57%, the concentration of the dissociated species can be calculated as follows:

[A-] = 0.57% * 8.0 x 10^-2 M = 4.56 x 10^-5 M

[H+] = [A-]

Since the dissociation is very small, we can assume that the concentration of the undissociated acid is equal to the initial concentration of the solution:

[HA] = 8.0 x 10^-2 M

So, the value of Ka can be calculated as:

Ka = [H+][A-] / [HA] = (4.56 x 10^-5 M)^2 / (8.0 x 10^-2 M) = 1.40 x 10^-10.

Therefore, the acid ionization constant for the acid is 1.40 x 10^-10.

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Mg-24 has a mass of 23.9850 and abundance of 78.99%.

Mg-25 has a mass of 24.9858 and abundance of 10.00%.

Mg-26 has a mass of 25.9826 and abundance of 11.01%.

When a substance is present in large quantities and is essentially unaltered by the reaction, it is said to be a reactant that is present in abundance in a chemical reaction. Abundance differs from excess in that excess refers to any reactant other than the limiting reagent; the amount by which a reactant is in excess is frequently specified, such as with terms like "twofold excess," which denotes that there is twice as much reactant as is required for the limiting reagent to completely react. In this case, if the reaction is successful, the amount of excess reactant will have been cut in half.

Sketch of graph is given below↓↓↓

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Answer:

Physicist Ernest Rutherford established the nuclear theory of the atom with his gold-foil experiment. When he shot a beam of alpha particles at a sheet of gold foil, a few of the particles were deflected. He concluded that a tiny, dense nucleus was causing the deflection.

3 chloride ions are required to neutralize the charge of +3 on aluminium ion and the ionic compound formed is AlCl3 .

Te term ionic compounds is defined as compounds made up of ions that produce charged particles when an atom gains or loses electrons. A cation is an ion charged positively, and an anion is an ion charged negatively.

Al has a charge of +3. Cl has a charge of -1. Therefore,3 chloride ions are required to neutralize the charge of +3 on aluminium and the neutral ionic compound AlCl3 is formed.

Thus, 3 Al3+ and 1 Cl− ions required to form a neutral ionic compound AlCl3.

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The correct option is D. 2-butanone organic compound has a branched hydrocarbon group.

Natural compounds are a substance that consists of covalently- bonded carbon and hydrogen and frequently with other elements. organic compounds examples are benzoic Acid, fragrant compounds, benzoic aldehyde, propanoic acid, butanoic acid, malonic acid, amines, heterocyclic compounds, VOC, benzoic acid, and diethyl malonate.

In chemistry, many authors bear in mind that an organic compound is any chemical compound that includes carbon-hydrogen or carbon-carbon bonds, although, the definition of "natural" versus "inorganic" varies from author to writer, and it's far a subject of debate. The chemicals of living matter are called organic compounds due to their affiliation with organisms and due to the fact they're carbon-containing compounds. organic compounds, which are the compounds associated with existence procedures, are the difficult count of a number of natural chemistry.

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The graph of reaction rate on the y-axis and temperature on the x-axis indicates that the reaction rate increases with an increase in temperature​.

The rate at which a chemical reaction occurs is known as the reaction rate, which is proportional to both the increase in a product's concentration per unit time and the decrease in a reactant's concentration per unit time. There is a wide range in reaction times.

The reaction rate increases with increase in:

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The number of atoms of oxygen in the reactants is 5 (3 from NO₂ and 2 from H₂O) and the number of atoms of oxygen in the products is 5 (1 from NO and 8 from HNO₃).

3NO₂(g) + H₂O(l) →→ NO(g) + 2HNO₃(aq)

Atom: Atoms are made up of smaller particles such as electrons, protons, and neutrons. These particles determine the properties of an atom and the elements they form.

Oxygen: Oxygen is the chemical element having symbol O and its atomic number will be 8. It is a member of the chalcogen group in the modern periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds.

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The enthalpy change (∆H) from the formation of 2H --> H₂ is: A. -432 kJ/mol.

Bond energy is the average energy needed to break the bond in a molecule within a reaction. We can use the bond energy to calculate the ∆H of the reaction as follows:

∆H = (∑ bond energies of the reactants) – (∑ bond energies of the products)

∆H = (2 x H) – (1 x H-H)

∆H = (2 x 0) – (432) kJ/mol

∆H = -432 kJ/mol

Hence, the enthalpy change from the formation of H₂ is: -432 kJ/mol.

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The number of photons that are produced in a laser pulse of 0.436 J

at 619 nm is 1.35 * 10¹⁸ photons.

The energy of a single photon at 619 nm wavelength

E = hc/λ

where:

h is Planck's constant = 6.63 x 10⁻³⁴ J•s.

c is speed of light = 3.0 * 10⁸ m/s

λ is wavelength = 619 nm or 6.19 * 10⁻⁷ m

E = 6.63 x 10⁻³⁴ * 3.0 * 10⁸ / 6.19 * 10⁻⁷

E = 3.21 * 10⁻¹⁹ J

1 photon is equivalent to 3.21 * 10⁻¹⁹ J

The number of photons = 0.436/3.21 * 10⁻¹⁹

The number of photons = 1.35 * 10¹⁸ photons.

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The number of milliliters of lead is: 368.81 mL

To calculate the number of milliliters of lead (density 11.3 g/mL) having a mass of 4.145 kg, you can use the following equation:

Therefore, 4.145 kg ÷ 11.3 g/mL = 368.81 mL

It is also important to remember that while this equation is useful for calculating the volume of a sample of a substance, it is not applicable to calculating the volume of a compound that contains multiple elements.

In such cases, the molar mass of the compound must be used instead. Additionally, the equation only works for substances with a constant density, as the density of a substance can vary depending on its temperature and pressure.

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The density of the object is 2.7 g/mL and it is aluminum.

We have to note that the density of the material is the ratio of the mass to the volume of the object. In the case the density was determined experimentally by plotting  the masses of several samples of an unknown substance against the corresponding volumes of water displaced by the samples.

We know that the density is the slope of the graph and the density of the object based on the statement in the question is 2.7 g/mL.

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