When is a sample of matter considered a pure substance?

Answer:

[tex]m=0.05m[/tex]

Explanation:

Hello,

In this case, molality is defined as:

[tex]m=\frac{n_{solute}}{m_{solvent}}[/tex]

Whereas the mass of the solvent is given in kilograms. In such a way, for 5 moles of solute and 100 kg of water, the molality turns out:

[tex]m=\frac{5mol}{100kg}\\ m=0.05\frac{mol}{kg}[/tex]

Now it is important to notice that the molal units (m) equals mol/kg, thereby:

[tex]m=0.05m[/tex]

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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 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.

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.

Answer

79 ml

Explanation

You have 237 237 ml of​ ammonia, whose strength is​ 100%.

If you want to make it 75%, then;

let 75%  ⇒ 237 ml of ammonia and

   25% ⇒  x ml of water.

∴ x = (25% ×237) / 75%

       = 5,925/75

         = 79 ml of water.

The mass of the compound will be equal to the sum of the masses of the individual elements.

According to the law of conservation of mass, the mass of the reactants in a chemical reaction must equal the mass of the products.

When sodium (Na), hydrogen (H), and oxygen (O) react to form a compound, such as sodium hydroxide (NaOH), the total mass of the compound produced will be equal to the combined masses of the individual elements that reacted.

This principle is fundamental in chemistry and ensures that mass is neither created nor destroyed during a chemical reaction.

Therefore, if you start with a certain amount of sodium, hydrogen, and oxygen, the total mass of these elements before the reaction will be exactly the same as the mass of the sodium hydroxide produced after the reaction.

Thus, the mass of the compound will be 'equal to' the sum of the masses of the individual elements.

Final answer:

Three physical properties of ionic compounds associated with ionic bonds are high melting and boiling points, brittleness, and poor conductivity in the solid state.

Explanation:

Three physical properties of ionic compounds that are associated with ionic bonds are:

High melting and boiling points: Ionic compounds have strong ionic bonds which require a large amount of energy to break. Thus, they have high melting and boiling points.

Brittleness: Ionic compounds are generally hard, but when a force is applied, the layers of ions shift causing ions of the same charge to come near each other. The repulsive forces between like-charged ions cause the crystal to shatter.

Poor conductivity in the solid state: Due to the strong ionic bonds, ions are unable to move freely in the solid state, making them poor conductors of electricity.

Physical properties can be perceived or observed without changing the structure of matter. These are used to detect and describe matter. Physical properties comprise: appearance, texture, color, odor, boiling point, melting point, density, solubility, and polarity  just to name a few.

In this case, the physical process used is boiling, which causes water to evaporate and the contents in the tea bag to become more soluble and can make the color to change. Also, the physical property of solubility relates to some of the components of the tea.

The term 'Volume' in physics defines the measure of the amount of space that a substance occupies. It is used across various equations and calculations in the study of physical sciences. Its applicability ranges from classroom learnings to real-life situations.

The term that best defines the measure of the amount of space a substance occupies is Volume. Volume is a fundamental concept in physical sciences and is often used in equations and calculations. Whether the substance is a liquid, a gas, or a solid, you can calculate its volume. For instance, the volume of a solid box is calculated by length * width * height, and the volume of a liquid in a cylindrical container would be calculated with π*radius2*height. Knowledge of volume can apply to real-life situations beyond the classroom as well, like working out how much water you can fit in a pool, or how much air is in your bedroom.

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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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The type of bonding and the number of covalent bonds an atom can form are determined by its valence electrons, which influence the atom's ability to share electrons and achieve a stable outer electron shell.

The type of bonding and the number of covalent bonds an atom can form with other atoms are determined by its valence electrons. These are the electrons that are found in the outermost shell of an atom and are involved in bonding. Atoms form covalent bonds by sharing valence electrons with other atoms to achieve a full outer shell, resembling the electronic configuration of noble gases. The number of covalent bonds that an atom can form is generally equal to the number of additional electrons needed to fill its outer shell.

For example, carbon, which has four valence electrons, can form four covalent bonds because it needs four more electrons to complete its octet. Similarly, nitrogen, with five valence electrons, typically forms three covalent bonds, as it requires three more electrons to have a full octet, and oxygen with six valence electrons most often forms two covalent bonds.

Answer:

bottom left corner

Explanation:

These are where their located

The metals in the bottom left corner of the periodic table are the most active in the sense that they are the most reactive. For example, lithium, sodium, and potassium all react with water.

The periodic table is a tabular array of chemical elements organized by atomic number, beginning with hydrogen and progressing to oganesson, which has the highest atomic number.

An element's atomic number is the number of protons in the nucleus of an atom of that element. There is one proton in hydrogen and 118 in oganesson.

Caesium, the most reactive metal in the periodic table, reacts violently, which is why it cannot be demonstrated in a classroom. When other common metals, such as iron and copper, are dropped into water, they produce no reaction.

Thus, The most reactive metals in the bottom left corner of the periodic table.

To learn more about the periodic table, follow the link;

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