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3 years ago

1.How many moles of each element are in 0.0250 mol of K 2 Cr O 4?

Chemistry

1 answer:

garik1379 [7]3 years ago

8 0

Answer:

1. In 0.0250 moles of potassium chromate there are 0.05 moles of potassium , 0.025 moles of chromium and 0.1 moles of oxygen are present.

2. In 4.50 moles of ammonium carbonate there are 9 moles of ammonium ions and 4.5 moles of carbonate ions are present.

Explanation:

Moles of potassium chromate = 0.0250 mol

Formula of potassium chromate = $K_2CrO_4$

1 mole of potassium chromate has 2 moles of potassium , 1 mole of chromium and 4 moles of oxygen.

Then in 0.0250 moles of potassium chromate:

Moles of potassium will be:

$2\times 0.0250 mol= 0.05 mol$

Moles of chromium will be:

$1\times 0.0250 mol= 0.025 mol$

Moles of oxygen will be:

$4\times 0.0250 mol= 0.1 mol$

Moles of ammonium carbonate = 4.50 mol

Formula of ammonium carbonate = $(NH_4)_2CO_3$

1 mole of ammonium carbonate has 2 moles of ammonium ion and 1 mole of carbonate ion.

Then in 4.50 moles of ammonium carbonate:

Moles of ammonium ion will be:

$2\times 4.50 mol= 9mol$

Moles of carbonate ions will be:

$1\times 4.50 mol= 4.5 mol$

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C3H8 + 5 O2 → 3 CO2 + 4 H2O

Reika [66]

Answer:

Mass = 112 g

Explanation:

Given data:

Mass of CO₂ produced = 90.6 g

Mass of oxygen needed = ?

Solution:

Chemical equation:

C₃H₈ + 5O₂ → 3CO₂+ 4H₂O

Number of moles of CO₂:

Number of moles = 90.6 g/ 44 g/mol

Number of moles = 2.1 mol

Now we will compare the moles of CO₂ and oxygen:

CO₂ : O₂

3 : 5

2.1 : 5/3×2.1 = 3.5

Mass of oxygen needed:

Mass = number of moles × molar mass

Mass = 3.5 mol × 32 g/mol

Mass = 112 g

7 0

3 years ago

Question 4(Multiple Choice Worth 4 points)

vitfil [10]

Answer:

The quantum number that describes the orientation of an orbital within a sublevel is the magnetic quantum number.

Explanation:

There are four quantum numbers in chemistry. These are the principal quantum number, the angular momentum quantum number, the magnetic quantum number, and the spin quantum number. These all follow these three foundational rules in chemistry.

The Pauli exclusion principle states that if two electrons inhabit the same orbital, they will spin in different directions.

Hund's rule states that if an orbital does not have an electron, an electron will need to fill it first before any of the other orbitals can have two electrons of differing spins.

The Aufbau principle states that all electrons will fill orbitals in an orderly fashion based on the quantum numbers. An attachment is included of this fill order for your reference.

The four quantum numbers for chemistry are:

The principal quantum number describes the sublevel in which the orbital is located. This occurs at n = 1, 2, 3, etc. all the way to 7.

The angular momentum quantum number describes the orbital that an electron fills. It will refer to the shape and the type of orbital.

The magnetic quantum number refers to the orientation of an orbital. Based on the angular momentum quantum number, there can be 1, 3, 5, or 7 orientations.

The spin quantum number refers to the Pauli exclusion principle. This number is assigned a negative or positive based on the orientation of the electron.

Therefore, because the magnetic quantum number is the one that refers to <u>the orientation of the orbital</u>, this is our answer.

5 0

3 years ago

Five students performed a Kjeldahl nitrogen analysis of a protein sample. The following weight % nitrogen values were determined

Sunny_sXe [5.5K]

Answer:

G_calculated = 1.756

The outlier should be rejected, as G_cal > G_tab (= 1.463) at 95 % confidence.

Explanation:

The Grubb's test is used for identifying an outlier in data, which is from the same population. For this, a statistical term, G, is calculated for the suspected outlier. If the calculated value is greater than the tabulated G value then the suspected value is rejected. This term is given as,

G_calculated = | suspect value - mean| / s

Here, suspect value is 13.8, mean is to be taken of all the data (including suspected value). s is the standard deviation of the sample data.

s is calculated from the following formula:

s = (Σ(xi - x)²/(N-1))^1/2

Here, x is the mean, which is 15.24, xi is individual value and N is the total number of data (5).

From the above formula, s is found to be

Standard Deviation, s = 0.820

Now for G value,

G_calculated = | 13.8 - 15.24| / (0.820)

G_ calculated = 1.756

The tabulated G value at 95 % confidence and N -1 (5 - 1 = 4) degree of freedom is, 1.463.

As calculated G (1.756) is greater than the tabulated G (1.463), the value 13.8 is considered an outlier at 95 % confidence.