The addition of heat to a pond causes serious problems for the aquatic plants because the increase in water temperature _______.

Answer : The water is made up of only one type of molecule and milk is made up of different type of molecules.

Explanation :

Pure substance : It is defined as a substance that is made by the combination of only one type of atom or only one type of molecule.

The pure substance can not be separated by simple physical methods.

Heterogeneous mixtures : It is a mixture that appears non-uniformly throughout the solution and the particle size or shapes are also different.

Homogeneous mixtures : It is a mixture that appears uniformly throughout the solution and the particle size or shapes are not different.

As water is considered as a pure substance because it is made up of only one type of molecule that means it is made up of two hydrogen atoms bonded to a single oxygen atom.

While on the other hand, milk is considered as a mixture because various substances (fats, proteins, water, lipids etc..) are present in milk. So, it is not a pure substance.

Water is considered a pure substance, while milk is not as water is made up of elements and milk is made up of mixture of compounds.

Pure substances are substances that are made up of only one kind of particle and have a fixed or constant structure.

Pure substances are further classified as elements and compounds.An element is a substance that consists of only one type or kind of atom. An element is a pure substance as it cannot be broken down or transformed into a new substance even by using some physical or chemical means. Elements are mostly metals, non-metals or metalloids.

Thus, water is considered  to be a pure substance, while milk is not as water is made up of elements and milk is made up of mixture of compounds.

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Answer : The given number in scientific notation will be, [tex]5.43\times 10^{-4}[/tex]

Explanation :

Scientific notation : It is the representation of expressing the numbers that are too big or too small and are represented in the decimal form with one digit before the decimal point times 10 raise to the power.

For example :

5000 is written as [tex]5.0\times 10^3[/tex]

889.9 is written as [tex]8.899\times 10^{-2}[/tex]

As we are given that the number is, 0.000543

This number is written in scientific notation as :

[tex]5.43\times 10^{-4}[/tex]

Hence, the given number in scientific notation will be, [tex]5.43\times 10^{-4}[/tex]

The number of protons, electrons, and neutrons in the 7Li+ ion can be determined by its atomic number and mass number. It has 3 protons, 3 electrons, and 4 neutrons.

Lithium-7 has three protons and four neutrons within its nucleus, making its mass number 7 and its atomic number 3. This means there are 3 protons, 3 electrons, and 4 neutrons in the 7Li+ ion.

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The concept of compressibility enables SCUBA tanks to contain a large amount of compressed air, which divers can use for breathing underwater despite the limited size of the tanks.

The principle of compressibility explains why the oxygen in a SCUBA tank is compressed. Gases are compressible, which means they can be packed into a smaller volume under higher pressure. This property is utilized in scuba diving to supply a diver with sufficient breathing gas underwater.

Because gases expand to fill their containers, at sea level (1 atm pressure), the air fills the available space. However, when pressure is applied, the air's volume decreases significantly, allowing more air to be packed into the same container.

For example, if the air in a typical scuba tank, which might have a volume of 13.2 liters and be pressurized to 153 atm, was transferred to a container at the standard 1 atm pressure, it would occupy about 2500 liters of volume. The high pressure in the tank therefore ensures that the diver has enough air to breathe while underwater for extended periods of time.

Changing the number of protons in an atom changes its element, altering neutrons results in isotopes with the same chemical properties, and changing electrons affects the atom's charge and reactivity without altering its identity.

The result of changing the number of each subatomic component -- protons, neutrons, and electrons -- on an atom would have different consequences:

For instance, carbon will always be carbon as long as it has 6 protons, regardless of the number of neutrons (isotopes) or electrons (ions) it may have. However, the physical and chemical properties of atoms and the resulting elements can vary greatly depending on the number and arrangements of subatomic particles.

Answer : The scientific notation of the given number is, [tex]4.8\times 10^{10}[/tex]

Explanation :

Scientific notation : It is defined as the way or representation of expressing the number that are too big or too small that is written in the decimal form. This means that, it always written in the form of power of 10.

For example : The number 200 is written as, [tex]2\times 10^2[/tex]

The given number is, 48,000,000,000 g

This number is written in scientific notation as :

[tex]48,000,000,000g=4.8\times 10^{10}g[/tex]

Therefore, the scientific notation of the given number is, [tex]4.8\times 10^{10}[/tex]

Answer: A chemical change has occurred.

Explanation: A chemical change is a change which results when there is a change in the chemical composition of the atoms.

Chemical changes are accompanied by:

a) Change in color

b) Absorption or release of heat

c) formation of precipitates

d) production of gas

[tex]Pb^{2+]+2Cl^-\rightarrow PbCl_2(s)[/tex]

The white powder is precipitates of lead chloride [tex]PbCl_2(s)[/tex] which do not dissolve.

Final answer:

A Selenium ion (Se) with an atomic number of 34 and 36 electrons has a charge of -2, making it a negatively charged ion, Se²⁻.

Explanation:

An ion with an atomic number of 34 and 36 electrons has a negative two charge. An atomic number of 34 corresponds to the element Selenium (Se). Normally, selenium has 34 electrons, equal to its number of protons, making it neutral. However, when it gains 2 additional electrons to have a total of 36, it becomes an anion (a negatively charged ion) with a charge of -2, denoted as Se²⁻. This gain in electrons increases its negative charge relative to its positive charge, leading to its overall negative charge.

The chemical formula for the selenous acid is H2SeO3. Its reaction with sodium hydroxide, which has a chemical formula of NaOH, will be a neutralization reaction forming a salt and water. This is depicted below.

             H2SeO3 + NaOH à Na2SeO3 + H2O

If we are to balance the chemical reaction then, we will have a final answer of,

        H2SeO3 + 2NaOH à Na2SeO3 + 2H2O

In its standard temperature and pressure, iron would exist as a solid. Therefore to make it into gas, we must heat it beyond its boiling point which is around 2,862°C. At that temperature, ordinary glass container would readily melt. Hence, it is impossible to contain gaseous iron in a glass container.

Final answer:

The mass of a pure gold cube with a volume of 3.20 cm³ is 61.76 grams. Using the density of gold (19.3 g/cm³), the mass is calculated by multiplying density by volume, with the final answer rounded to three significant figures as 61.8 grams.

Explanation:

To calculate the mass of a pure gold cube with a given volume, you use the density of gold. The density (d) of gold is known to be 19.3 g/cm³. Thus, if the volume of the gold cube is 3.20 cm³, the mass (m) is calculated as follows:

m = d × V

Where m is the mass, d is the density, and V is the volume. Plugging in the values:

m = 19.3 g/cm³ × 3.20 cm³

m = 61.76 grams

Therefore, the mass of the gold cube is 61.76 grams. We limit our final answer to three significant figures, so the mass is 61.8 grams.

Covalent bonds involve the sharing of electrons between atoms, while ionic bonds involve the transfer of electrons from one atom to another.

The fundamental difference between covalent bonds and ionic bonds is that in covalent bonds, electrons are shared between atoms, whereas in ionic bonds, electrons are transferred from one atom to another.

In covalent bonds, the atoms are nonmetals and they share electrons to achieve a stable electron configuration. Examples include the bond between two hydrogen atoms in a hydrogen molecule (H2) and the bond between carbon and oxygen in carbon dioxide (CO2).

In ionic bonds, one atom loses electrons to become a positively charged ion (cation), while another atom gains those electrons to become a negatively charged ion (anion). These oppositely charged ions are then attracted to each other and form an ionic bond. An example is the bond between sodium (Na+) and chlorine (Cl-) in sodium chloride (NaCl).

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The correct statement for a chemical change that gives off heat is that the molecule types change and the process is exothermic, as energy is released to the surroundings.

When an unknown substance undergoes a chemical change that gives off heat, the process is exothermic, and the types of molecules before and after the change are different. A chemical change that releases heat indicates that energy is a product of the reaction.

This is contrasted with an endothermic process where heat is absorbed, and the surroundings become colder. In exothermic reactions, bonds are formed which release more energy than the energy needed to break bonds in the reactants, hence the heat given off to the surroundings.

The correct statement for a chemical change that produces heat is: The types of molecules of the substance before and after the chemical change are different, and the change was exothermic.

Complete Question - An unknown substance undergoes a chemical change that gives off heat. Which statement is true?

The atomic mass of gallium on the newly discovered planet is calculated to be 69.65704 amu, based on the given abundances and masses of its isotopes 69ga and 71ga.

To calculate the atomic mass of gallium based on the given abundances and masses of its isotopes,  we can use the formula: Atomic mass = (% abundance of isotope 1 × mass of isotope 1) + (% abundance of isotope 2 × mass of isotope 2), where percentages are converted into decimal form. Given, 69ga has an abundance of 60.11% (or 0.6011) and a mass of 68.7200 amu, and 71ga has an abundance of 39.89% (or 0.3989) and a mass of 70.9200 amu.

The calculation is therefore: (0.6011 × 68.7200 amu) + (0.3989 × 70.9200 amu).

This equals: 41.359532 amu + 28.297508 amu = 69.65704 amu.

Therefore, the atomic mass of gallium for this location is 69.65704 amu.

The atomic mass of gallium on the newly discovered planet is approximately 69.6077 amu.

To determine the atomic mass of gallium on the newly discovered planet, the contributions of both isotopes ⁶⁹Ga and ⁷¹Ga must be considered based on their abundances and atomic masses.

⁶⁹Ga abundance: 60.11%

⁷¹Ga abundance: 39.89%

Mass of ⁶⁹Ga: 68.7200 amu

Mass of ⁷¹Ga: 70.9200 amu

Convert abundances from percentages to decimals:

⁶⁹Ga : 60.11% = 0.6011

⁷¹Ga : 39.89% = 0.3989

Calculation of atomic mass:

Atomic mass = (fractional abundance of ⁶⁹Ga × mass of ⁶⁹Ga) + (fractional abundance of ⁷¹Ga × mass of ⁷¹Ga)

[tex]\text{Atomic mass} &= (0.6011 \times 68.7200 \, \text{amu}) + (0.3989 \times 70.9200 \, \text{amu}) \\[/tex]

Atomic mass = 41.3092 amu + 28.2985 amu

Atomic mass = 69.6077 amu

Final answer:

Similar chemical properties in elements arise from their groupings in the periodic table. Bromine and Fluorine are paired as halogens; Magnesium and Strontium as alkaline earth metals; and Sulfur and Oxygen as chalcogens.

Explanation:

Elements that exhibit similar chemical properties are often found in the same group or family on the periodic table. The elements provided can be sorted into pairs based on their chemical behaviors and position in the periodic table:

In summary, similar properties in elements are a result of their position within the same group on the periodic table. For example, bromine and fluorine are both halogens, while magnesium and strontium are alkaline earth metals.

To find the edge length of a cube made of gold, divide the mass of the gold sample by its density and take the cube root of the result.

The edge length of a sample of gold, if it is in the form of a cube, can be determined using the concept of density. The density of gold is 19.3 g/cm³. To find the edge length, we need to divide the mass of the gold sample by its density. For example, if the mass of the gold sample is 10 grams, the volume is 10 g / 19.3 g/cm³ = 0.52 cm³. Since the sample is a cube, all three dimensions are equal, so the edge length would be the cube root of the volume. In this case, the edge length would be approximately 0.8 cm.

The law of definite composition states that a chemical compound always consists of the same elements in a fixed ratio by mass, regardless of how or where it's formed. For example, water always contains hydrogen and oxygen in a 1:8 mass ratio. This law is crucial for understanding chemical reactions and the conservation of mass.

The law of definite composition, also known as the law of definite proportions, is a fundamental concept in chemistry. This law states that a chemical compound, no matter how it is formed or where it is found, will always consist of the same elements in a fixed ratio by mass. For example, water (H2O) is always composed of hydrogen and oxygen in a 1:8 mass ratio, meaning that there are always 8 grams of oxygen for every 1 gram of hydrogen.

This law has significant implications for chemical reactions. Because compounds always have a definite composition, the mass of the reactants in a chemical reaction always equals the mass of the products. This reflects the principle of conservation of mass.

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The law of definite composition, also known as the law of constant composition, is a fundamental concept in Chemistry. This law states that any given chemical compound will always contain the same elements in the exact same proportions by mass, regardless of the sample's origin or quantity.

Definition and Origin: The law of definite composition was formulated by Joseph Proust in the late 18th century. His experiments showed that chemical compounds contain elements in a fixed ratio by mass.

Fixed Ratios: For example, water (H₂O) is always composed of two hydrogen atoms and one oxygen atom. This 2:1 ratio in the number of atoms translates to a consistent mass ratio because each element has a specific atomic mass.

Mass Proportions: To illustrate with masses, the atomic mass of hydrogen is approximately 1 amu (atomic mass unit) and that of oxygen is about 16 amu. Therefore, in a water molecule, the mass ratio of hydrogen to oxygen is roughly 2 (from 2 hydrogen atoms) to 16, or simplified to 1:8.

Consistency Across Samples: No matter where you find a sample of water, whether from a river or distilled in a lab, its composition by mass will always be around 88.8% oxygen and 11.2% hydrogen.

Implications: This law helps in predicting and understanding chemical reactions because knowing the fixed ratios allows chemists to determine the quantities of reactants needed to produce a certain amount of a compound.

When solid zinc fluoride (ZnF2) dissolves in water, it dissociates into its constituent ions to form aqueous zinc ions (Zn^2+) and fluoride ions (F^-). This transformation represents a physical change known as dissociation. This reaction is typical for strong electrolytes like zinc fluoride due to the ionic bonds within the compound.

The compound zinc fluoride (ZnF2) is a strong electrolyte, which means that it completely dissociates into its constituent ions when dissolved in water. The process of dissociation occurs when the ions in the solid separate and disperse uniformly throughout the solution. This is facilitated by water molecules that surround and solvate the ions, reducing the strong electrostatic forces between them.

When solid zinc fluoride dissolves in water, it forms aqueous zinc ions (Zn^2+) and fluoride ions (F^-). This can be represented by the equation:

ZnF2 (s) -> Zn^2+ (aq) + 2F^- (aq)

This transformation is a physical change known as dissociation. The term 'aq' denotes that the ions are in an aqueous solution, indicating that they have been solvated by water molecules. It's noteworthy that the compound zinc fluoride, by nature of it being an ionic bond, is a strong electrolyte, hence it will nearly completely dissociate when dissolved in water.

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The formation of rust on metal is a chemical change because it involves new chemical bonds forming between iron and oxygen, resulting in the new substance, iron oxide or rust.

Is rust forming on metal a chemical or physical change? The formation of rust on metal is a chemical change. Rust is iron oxide, a different kind of matter than the iron, oxygen, and water present before the rust formed. The reaction that takes place is Fe + O₂ → Fe₂O₃, indicating that new chemical bonds have been formed, leading to the creation of a new substance. Color change is a common indicator of a chemical change, and in the case of rust formation, we observe the metal transitioning from its original color to an orange or red flaky substance. This transformation is due to the chemical reaction of iron with oxygen, commonly referred to as corrosion. Rusting is an expensive problem, causing significant financial impact due to the damage it causes to metal structures and items.

The mass of 5.80 × 10^23 atoms of silver (Ag) can be found by first determining the number of moles of Ag this represents using Avogadro's number, then using the atomic mass of Ag to calculate the mass.

To find the mass of 5.80 × 1023 atoms of silver (Ag), we use Avogadro's number, which states there are 6.022 × 1023 atoms in one mole of any substance. First, we find the number of moles in 5.80 × 1023 atoms of Ag by dividing the given number of atoms by Avogadro's number.

Moles of Ag = (5.80 × 1023) / (6.022 × 1023)

Next, we calculate the mass of these moles of Ag using atomic mass of silver (107.87 g/mol).

Mass of Ag = Moles of Ag x Atomic mass of Ag

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By stoichiometry and assume that:

CxH2xOy + zO2 -> xCO2 + xH2O 

CO2: 9.48/44 = 0.215 mmol 
H2O: 3.87/18 = 0.215 mmol 
mass of C = 0.215 * 12 = 2.58 mg 
mass of H = 0.215 * 2 * 1 = 0.43 mg 
mass of O in ethylbutyrate = 4.17 - 2.58 - 0.43 = 1.11 mg 
So C/O = 2.58/1.11 ≈ 3 

Thus we have C3H6O

Answer: The empirical formula for the given compound is [tex]C_3H_6O[/tex]

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=9.48mg=9.48\times 10^{-3}g[/tex]

Mass of [tex]H_2O=3.87mg=3.87\times 10^{-3}g[/tex]

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

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

So, in [tex]9.48\times 10^{-3}g[/tex] of carbon dioxide, [tex]\frac{12}{44}\times 9.48\times 10^{-3}=2.58\times 10^{-3}g[/tex] of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in [tex]3.87\times 10^{-3}g[/tex] of water, [tex]\frac{2}{18}\times 3.87\times 10^{-3}=4.30\times 10^{-4}g[/tex] of hydrogen will be contained.

For calculating the mass of oxygen:

Mass of oxygen in the compound = [tex](4.17\times 10^{-3})-[(2.58\times 10^{-3})+(4.30\times 10^{-4})]=1.16\times 10^{-3}g[/tex]

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon =[tex]\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{2.58\times 10^{-3}g}{12g/mole}=2.15\times 10^{-4}moles[/tex]

Moles of Hydrogen = [tex]\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{4.30\times 10^{-4}g}{1g/mole}=4.30\times 10^{-4}moles[/tex]

Moles of Oxygen = [tex]\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{1.16\times 10^{-3}g}{16g/mole}=7.25\times 10^{-5}moles[/tex]

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is [tex]7.25\times 10^{-5}[/tex] moles.

For Carbon = [tex]\frac{2.15\times 10^{-4}}{7.25\times 10^{-5}}=2.96\approx 3[/tex]

For Hydrogen  = [tex]\frac{4.30\times 10^{-4}}{7.25\times 10^{-5}}=5.93\approx 6[/tex]

For Oxygen  = [tex]\frac{7.25\times 10^{-5}}{7.25\times 10^{-5}}=1[/tex]

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 3 : 6 : 1

Hence, the empirical formula for the given compound is [tex]C_3H_6O_1=C_3H_6O[/tex]

Answer: Option (b) is the correct answer.

Explanation:

When two atoms of the same element has different number of neutrons but same number of protons then it is known as an isotope.

For example, isotopes of carbon are [tex]^{12}_{6}C[/tex] and [tex]^{13}_{6}C[/tex].

Also, when two atoms of the same element have same number of protons then their chemical properties remain the same.

Therefore, we can conclude that two atoms of the same element must have the same number of protons.

Elements in the same group have similar valence electron configurations leading to similar chemical properties, while elements in the same period have the same number of electron shells but differing valence electrons causing changes in atomic radius and ionization energy.

Similarities Amongst Elements Within a Group

Elements within a group, also known as a column on the periodic table, share several important similarities. These elements typically have the same number of electrons in their outermost or valence shell, leading to similar chemical properties. For instance, the alkali metals in Group 1 all have one electron in their outermost shell and are very reactive, especially with water. As you move down a group, atomic size and reactivity tend to increase due to the addition of more electron shells.

Similarities Amongst Elements Within a Period

A period is a horizontal row on the periodic table. Elements in the same period have the same number of electron shells but differ in the number of electrons within the valence shell. Moving from left to right across a period, the atomic radius usually decreases, and ionization energy increases as electrons are added to the same shell and protons to the nucleus, creating a stronger pull on the electrons.

The organization of the periodic table facilitates the understanding of these trends, with elements sorted by increasing atomic number and structured in periods and groups to reflect periodic trends such as atomic size, reactivity, and ionization energy. This organization reflects the periodic recurrence of elements with similar properties and allows chemists to predict chemical behaviors based on position within the table.