CHEMISTRY HIGH SCHOOL

Please help me in this.
i'll seriously mark you brainly.
please help.

Answers

Answer 1

Answer:

Answer:

First box: 3

Second box: 4

Third box: 3

Fourth box: 4

Explanation:

I tried out various numbers, but got 3 and 4 because:

3PbI4 + 4CrCl3 -----> 3PbCl4 + 4CrI3

Each term cancels put.

3Pb --> 3Pb

4Cr --> 4Cr

and so forth...

Hope this helps!

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Earth's first semi-permanent atmosphere consisted of abundant water vapor, carbon dioxide, nitrogen, ammonia, and traces of methane. these gases came from

Answers

organic compounds from the Cambrian era

What element has the electron configuration 1s2 2s2 2p6 3s2 3p2?

Answers

The sulfur (S) element of the periodic table is represented by the electron configuration $1s^2 2s^2 2p^6 3s^2 3p^2$ .

The arrangement of electrons within the energy levels or orbitals of an atom is represented by electronic configuration. Sulfur has 16 electrons in its structure. The numbers in the electronic configuration represent the principal energy levels—1, 2, and 3—as well as the orbital—s or p—that the electrons are in.

Detail analysis of electron arrangement:

The first energy level (n = 1) represents the presence of two electrons in the symbol $1s^2$ 1s orbital.
The symbol $2s^2$ indicates the presence of two electrons in the second energy level (n = 2) and the 2s orbital.
The $2p^6$ symbol indicates the presence of 6 electrons in the second energy level (n = 2) and 2p orbitals.
The third energy level, or $3s^2$ , refers to the presence of two electrons in the 3s orbital (n = 3).
$3p^2$ stands for the third energy level (n = 3), and indicates that two of the three p orbitals hold two electrons.

When these electronic configurations are combined, the electron configuration of sulfur (S) is represented by $1s^2 2s^2 2p^6 3s^2 3p^2$ .

Learn more about Electronic configuration, here:

brainly.com/question/29184975

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Count the number of electrons = 2+2+6+2+2= 14

So, it must be SILICON.

Tendons attach muscles to bones.
True
False

Answers

Absolutely true

Just in case you do get it, a ligament will attach a bone to a bone, just as a fun fact

Answer:

This is true.

Explanation:

Pb(NO3)2 (aq) + 2 NaI (aq) --> PbI2 (s) + 2 NaNO3 (aq)Starting with with 50.0 grams of Pb(NO3)2 and 30.0 grams of NaI:
A. What is the limiting reagent?
B. How many grams of the excess reactant remains?
C. How many grams of each product is formed?
D. If 12 grams of NaNO3 actually formed in the reaction, what is the percent yield of this reaction?

Answers

Answer:

Explanation:

Pb(NO3)2 (aq) + 2 NaI (aq) --> PbI2 (s) + 2 NaNO3 (aq)

MM for each compound -

Pb(NO3): 207 + 14x2 + 16x3x2 = 331

PI2: 207 + 127x2 = 461

NaI: 23 + 127 = 150

NaNO3: 23 + 14 + 16x3 = 85

Moles of Pb(NO3)2 = 50/331 = 0.15

Moles of NaI = 30/150 = 0.2

Ratio of moles is 1:2

So NaI is limiting

Limited to 0.2/2 = 0.1 mole of Pb(NO3)2

Excess = 0.15 - 0.1 = 0.05 mole

Mass remains = 0.05x331 = 16.55 grams

Moles of NaNO3 formed = Moles of NaI reacted = 0.2

Mass = 0.2x85 = 17 grams

Moles of PbI2 formed = Moles of Pb(NO3)2 reacted = 0.1

Mass = 0.1x461 = 46.1 grams

If 12 grams of NaNO3 actually formed in the reaction,

percent yield = 12/17x100% = 70.6%

Answer:

Explanation:

Moles of Pb(NO3)2 = mass/molecular mass

= 50.0 grams/(207.20*1 + 14.01*2 + 16*6)

= 50.0 grams/331.22

= 0.15 moles

Moles of NaI

= 30/(22.99+126.9)

= 30/149.89

= 0.2 Moles

A. NaI is less 2x Pb(NO3)2 so NaI is the limiting reagent.

B. The ratio is 1 to 2 so there is 0.15 - 0.2/2 = 0.05 mole

or 16.78 grams of Pb(NO3)2 left.

C. As NaI is limiting, only 0.2 Moles of NaNO3 is formed.

Mass = Moles * Molecular Mass

Molecular Mass of NaNO3 can be calculated as:

Na - 22.99

N - 14.01

O - 3(16) = 48

23+14+48 = 85gram / mole

Thus, Mass = 0.2*85 = 17 gram of NaNO3

Mass is conserved in a chemical reaction.

Mass of PbI2 can be calculated as:

50+30-16.78-17

= 46.3 gram of PbI2

Mass =

12.75

Thus, 12.75g of Sodium Nitrate can be formed

What is the mass of 2.25 moles of manganese(lv) sulfide(MnS2)

Answers

Explanation:

Number of moles is defined as mass divided by molar mass of the substance or atom.

Mathematically, No. of moles = $(mass)/(molar mass)$

It is known that molar mass of $MnS_(2)$ is 119.058 g/mol and number of moles is given as 2.25 mol.

Therefore, calculate mass of $MnS_(2)$ as follows.

No. of moles = $(mass)/(molar mass)$

2.25 mol = $(mass)/(119.058 g/mol)$

mass = 267.88 g

Thus, we can conclude that mass of 2.25 moles of manganese(lv) sulfide(MnS2) is 267.88 g.

Final answer:

The mass of 2.25 moles of Manganese (V) Sulfide (MnS2) can be calculated by multiplying the molar mass of MnS2 (119.08 g/mol) by the number of moles (2.25). The result is approximately 267.93 grams.

Explanation:

The question asks about the mass of 2.25 moles of manganese (V) Sulfide (MnS2). We can calculate this using the molar mass of MnS2. The molar mass of manganese (Mn) is approximately 54.94 g/mol, and the molar mass of Sulfur (S) is approximately 32.07 g/mol. To find the molar mass of MnS2 we add up the molar mass of Mn and twice the molar mass of S (because we have 2 S atoms). Therefore the molar mass of MnS2 = 54.94 + 2*(32.07) = 119.08 g/mol. To find the mass in grams, we multiply this molar mass by the number of moles. Hence, the mass of 2.25 moles of MnS2 = 2.25 * 119.08 = 267.93 grams.