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3 years ago

Which type of particle retains the identity of an element during a chemical reaction? a) electron

1 answer:

3 0

The answer is C. atom. An atom is the smallest fraction of a chemical element that can ever exit. An atom consists three particles which are the protons neutrons and electrons. Electrons are found around the center of the atom. The protons and neutrons are found in the center of the atom

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describe the independent and dependent variables in this experiment then describe the other variables that need to be controlled

uranmaximum [27]

independent variable is being controlled and the dependent variable is being tested and being easured in a scientific experiment

3 0

3 years ago

When the reactive alkali metal sodium is reacted with poisonous chlorine gas, sodium chloride or table salt is produced. Is mass

PIT_PIT [208]

Answer:

Yes, Mass is conserved.

Explanation:

Every chemical reactions obey the law of conservation of mass. The law of conservation of mass states that in chemical reactions, mass is always constant.

Equation:

2Na + Cl₂ → 2NaCl

From the equation above, one can observe that the reaction started using 2 atoms of Na and it produced 2 atoms of the same element in NaCl. A molecule of Cl produced 2 atoms of Cl in the NaCl

Design a simple experiment to support your answer:

Aim: To demonstrate the law of conservation of mass

One Na atom weighs 23g

Two Na atom will weigh 2 x 23 = 46g

1 atom of Cl is 35.5g

1 molecule of Cl containing two atoms of Cl will weigh 2 x 35.5 = 71g

Total mass of reactants = mass of 2Na + 1Cl₂ = (46 + 71)g = 117g

On the product side, Mass of 1 NaCl = 23+ 35.5 = 58.5g

Two moles of NaCl will give 2 x 58.5g = 117g

Since the mass on both side is the same, one can say mass is conserved.

7 0

3 years ago

Given a gas whose temperature is 418 K at a pressure of 56.0 kPa. What is the pressure of the gas if its Temperature changes to

Rainbow [258]

Answer: P₂=0.44 atm

Explanation:

For this problem, we are dealing with temperature and pressure. We will need to use Gay-Lussac's Law.

Gay-Lussac's Law: $\frac{P_{1} }{T_{1} } =\frac{P_{2} }{T_{2} }$

First, let's do some conversions. Anytime we deal with the Ideal Gas Law and the different laws, we need to make sure our temperature is in Kelvins. Since T₂ is 64°C, we must change it to K.

64+273K=337K

Now, it may be uncomfortable to use kPa instead of atm, so let's convert kPa to atm.

$56.0kPa*\frac{1000Pa}{1kPa} *\frac{atm}{101325Pa} =0.55atm$

Since our units are in atm and K, we can use Gay-Lussac's Law to find P₂.

$P_{2} =\frac{T_{2} P_{1} }{T_{1} }$

$P_{2}=\frac{(337K)(0.55atm)}{418K}$

P₂=0.44 atm

8 0

3 years ago

Write the full ground state electron configuration of C − C− . electron configuration: Which neutral atom is isoelectronic with

stepan [7]

Answer: 1. Is2 2s2 2p3

2. Nitrogen

Explanation: The number of electron present In C = 6

But an extra electron is added since the charge on C is -1, this therefore makes the total electron 7.

1. By arrangement, the Electronic configuration is therefore;

Ans: 1s2 2s2 2p3

2. It is explained how C has 7 electrons, we can proceed then.

Neutral atom have atomic number of 7.

The element with atomic number of 7 is;

Ans: NITROGEN

7 0

3 years ago

You are given solutions of hcl and naoh and must determine their concentrations. you use 27.5 ml of naoh to titrate 100.0 ml of

Dafna1 [17]

1) Start by standardizing the solution of NaOH by using the solution of H2SO4 whose concentration is known.

2) Equation:

2Na OH + H2SO4 --> Na2 SO4 + 2H2O

3) molar ratios

2 mol NaOH : 1 mol H2SO4

4) Number of moles of H2SO4 in 50.0 ml of 0.0782 M solution

M = n / V => n = M*V = 0.0782 M * 0.050 l = 0.00391 mol H2SO4

5) Number of moles of NaOH

2 moles NaOH / 1mol H2SO4 * 0.00391 mol H2SO4 = 0.00782 mol NaOH

6) Concentration of the solution of NaOH

M = n / V = 0.00782 mol / 0.0184 ml = 0.425 M

7) Standardize the solution of HCl

Chemical reaction:

NaOH + HCl --> NaCl + H2O

8) Molar ratios

1 mol NaOH : 1 mol HCl

9) Number of moles of NaOH in 27.5 ml

M = n / V => n = M * V = 0.425 M * 0.0275 l = 0.01169 moles NaOH

10) Number of moles of HCl

1 mol HCl / 1mol NaOH * 0.01169 mol NaOH = 0.01169 mol HCl

11) Concentration of the solution of HCl

M = n / V = 0.01169 mol / 0.100 l = 0.1169 M

Rounded to 3 significant figures = 0.117 M

Answers:

[NaOH] = 0.425 M
[HCl] = 0.117 M

3 0

3 years ago