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2 years ago

Atomic #

Chemistry

1 answer:

Anon25 [30]2 years ago

7 0

In the modern periodic table, the elements are listed in order of increasing atomic number. The atomic number is the number of protons in the nucleus of an atom. The number of protons define the identity of an element (i.e., an element with 6 protons is a carbon atom, no matter how many neutrons may be present).

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The number of mole of a molecule is defined as its mass per molar mass. Using # mol = n, mass = m and molar mass = M and given t

Citrus2011 [14]

Given:
n = 0.0021 mol
M = 44 gram/mol

Required: m or the mass of the molecule

Solution:

M = m/n

Rearranging the expression,

m = M x n
m = 44 g/mol x 0.0021 mol

Evaluating the expression and cancelling units, we obtain,

m = 0.0924 grams

M is the molar mass. This value is very useful in chemistry calculations especially in calculating the amounts of reactants and products for a chemical reaction.

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3 years ago

Calcutale Grxn for the following equation at 25°C: 4KClO3(s) → 3KClO4(s) KCl(s)

Step2247 [10]

Answer:

-133.2 kJ

Explanation:

Let's consider the following balanced equation.

4 KClO₃(s) → 3 KClO₄(s) + KCl(s)

We can calculate the standard Gibbs free energy of the reaction (ΔG°rxn) using the following expression.

ΔG°rxn = 3 mol × ΔG°f(KClO₄(s)) + 1 mol × ΔG°f(KCl(s)) - 4 mol × ΔG°f(KClO₃(s))

ΔG°rxn = 3 mol × (-303.1 kJ/mol) + 1 mol × (-409.1 kJ/mol) - 4 mol × (-296.3 kJ/mol)

ΔG°rxn = -133.2 kJ

5 0

3 years ago

A 1M solution is made of each item in a pair. When would this combination create a buffer? Chose the pairs below that you could

monitta

Answer:

b. HCOOH/ NaHCOO.

Explanation:

A buffer system may be formed in one of two forms:

A weak acid with its conjugate base.

A weak base with its conjugate acid.

Chose the pairs below that you could use to make a buffered solution.

a. HCI/NaOH. NO. HCl is a strong acid and NaOH is a strong base.

b. HCOOH/ NaHCOO. YES. HCOOH is a weak acid and HCOO⁻ (coming from NaHCOO) is its conjugate base.

c. HNO₂/H₂SO₃. NO. Both are acids and they are unrelated to each other.

d. NaNO₃/ HNO₃. NO. HNO₃ is a strong acid.

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2 years ago

Please help me with this basic organic conversion. use the shortest way to do it

jonny [76]

Answer:

See explanation

Explanation:

This conversion must go through a sequence of steps as i have shown in the image attached to this answer.

The acetone is converted to propan-2-ol using LiAlH4, THF and acid. The propan-2-ol may be converted to propene by E2 elimination. Addition of HBr yields 2-bromo propane.

The Wurtz reaction converts 2-bromo propane to 2,3- dimethyl butane. This can be brominated in the presence of light to yield 3-bromo-2,3-dimethyl butane. Elimination of HBr using a base leads to the formation of the required product as shown.

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2 years ago

A little aluminum boat (mass of 14.50

Valentin [98]

When the volume is 450 cm3 so the boat will displace 450 g.

so we have 450 g - 14.5g = 435.5 left

so to get how many pennies can be added to the boat before it sinks can be determined by:

divided the mass for the one penny:

no.of Penny = 435.5 / 2.5g

= 174.2

∴ the boat will float with 174 pennies and will start to sink with 175

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2 years ago