The fur on an arctic polar bear appears white all year. The color of the fur is an example of

How many moles are in 1.05 g of gold (Au)?

Wittaler [7]

Answer:

0.005 mol

Explanation:

Moles is denoted by given mass divided by the molecular mass ,

Hence ,

n = w / m

n = moles ,

w = given mass ,

m = molecular mass .

From the question ,

w = given mass of Gold = 1.05 g ,

m = molecular mass of Gold = 197 g/mol

Hence , moles can be calculated as -

n = w / m = 1.05 g / 197 g/mol = 0.005 mol

7 0

3 years ago

The temperature at which the reaction is occurring is increased

svetlana [45]

The addition of heat energy to a system always causes the temperature of that system to increase. This is always true because you are adding heat of a substance to increase its temperature. For example, you are going to drink a cup of coffee. And you wanted it hot to boost your attention. So you have to use hot water. In order for your water to become hot or warm, you need boil it in a kettle. Note that you are going to use an electric stove. The electric stove gets it energy from the source giving it a hotter temperature to the water in the kettle. You are applying heat energy to warm the water. So, the statement is true.

6 0

3 years ago

Suppose an adult is encased in a thermally insulating barrier so that all the heat evolved by metabolism of foodstuffs is retain

mihalych1998 [28]

Given:
Q = 9.4 kJ/(kg-h), the heat production rate
c = 4.18 J/(g-K), the heat capacity
t = 2.5 h, amount of time

Note that
c = 4.18 J/(g-K) = 4180 J/(kg-K) = 4.18 kJ/kg-K)

Consider 1 kg of mass.
Then
Qt = cΔT
where ΔT is the increase in temperature (°K)
(1 kg)*(9.4 kJ/(kg-h))*(2.5 h) = (1 kg)*(4.18 kJ/(kg-K))*(ΔT K)
23.5 = 4.18 ΔT
ΔT = 23.5/4.18 = 5.622 K = 5.622 °C

Answer: 5.62 K (or 5.62 °C)

7 0

3 years ago

Fill in the missing mass number and atomic number for each of these particles or types of radiation.

Akimi4 [234]

Answer:

Particle / mass number atomic number

type of radiation

alpha / ⁴₂ He 4 2

beta / e⁰ 0 - 1

gamma / γ 0 0

neutron / n 1 0

Explanation:

These are the basic types of radiation: alpha (α), beta (β), gamma (γ), and neutrons (n).

The radiation is emitted by unstable nuclei when undergo radiactive decay or by nuclei that are shooted by other particles.

Alpha radiation (⁴₂ He):

They are nuclei of helium-4 atoms: 2 protons and 2 neutrons.

Hence, the atomic number, which is the number of protons, of these particles, is 2; and the mass number, which is the sum of protons and neutrons, is 2 + 2 = 4.

The symbol of this radiation is ⁴₂ He, where the superscript to the left of the chemical symbol is the mass number and the subscript to the left of the chemical symbol is the atomic number.

Beta (⁰₋ ₁ e)

These are electrons emiited from an unstable nucleus. The symbols used for this particle are either ⁰₋ ₁β or ⁰₋ ₁e.

The superscript 0 indicates that the relative mass of this particle is practically zero and the subscript -1 tells that the emission of electrons increases the atomic number of the nucleus that emits it.

Gamma (⁰₀γ)

The gamma rays are electromagnetic radiation of high (the highest) energy.

The both superscript and subscript are zero, meaning that this radiation does not change either the mass or atomic numbers of the nucleus.

Neutron (¹₀n):

Neutrons are also emiited from the nucleus and so they may be considered a radiation.

The atomic number of neutrons is 0 (since it does not have protons) and its mass number is 1.

4 0

4 years ago

Read 2 more answers

Determine the molarity of a solution prepared by dissolving 0.198 g of "KHP" (C8H5O4K) in enough water to make 125 mL of solutio

rosijanka [135]

Answer:

0.007756M KHP; 0.0009695 moles NaOH reacts; 0.03488M NaOH.

Explanation:

Potassium hydrogen phthalate, KHP, is a salt used as standard to determine concentration of basic solutions as NaOH solutions.

To find molarity of the KHP solution we need to convert mass of KHP to moles and divide this in 125mL = 0.125L:

Moles KHP -Molar mass: 204.22g/mol-:

0.198g * (1mol / 204.22g) = 0.0009695 moles KHP

Molarity:

0.0009695 moles KHP / 0.125L = 0.007756M KHP

NaOH reacts with KHP as follows:

NaOH + KHP → Na⁺ + KP⁻ + H₂O

That means 1 mole of NaOH reacts per mole of KHP, that means moles of NaOH that reacts are = Moles of KHP added:

0.0009695 moles NaOH reacts

In 27.80mL = 0.02780L the NaOH was contained. Molarity is:

0.0009695 moles NaOH / 0.02780L =

0.03488M NaOH

4 0

3 years ago