Elements in this family have 1 valence electron?

What is the percent of iron (Fe) in 325g of FeCl3

saveliy_v [14]

Answer:

Element Symbol Mass Percent

Chlorine Cl 65.571%

Iron Fe 34.429%

Explanation:

8 0

3 years ago

How do cells reproduce? ∵∵∵∵∵∵∵∵∵∵∵∵∵∵∵∵∵∵

lora16 [44]

Answer:

Cells divide to reproduce. There are two primary methods used, one for somatic cells, which compose the organism’s body, and one for reproductive cells, or gametes.

Scientists call the process of somatic cell division mitosis. Mitosis has six distinct steps in which the cell organizes and copies the DNA in the nucleus. Once copied, each new cell has its own copy of the DNA. The six steps of mitosis are prophase, prometaphase, metaphase, anaphase, telophase and cytokinesis. Some authorities consider the non-dividing portion of the cell’s lifecycle, known as interphase, to be one of seven steps involved in mitosis; however, interphase cells are not actively dividing.

Sex cells, such as sperm or eggs, must divide differently. Sex cells only possess one-half of the DNA that makes up a new animal. That way, when they combine, the resulting organism gets half of its DNA from its mother and half from its father. Because sex cells only want half of the DNA in each cell, they go through a different division process called meiosis. In meiosis, the cells split a second time, which yields four daughter cells rather than two as with mitosis; however, this provides each daughter cell with 23 chromosomes in contrast to the 46 chromosomes in somatic cells.

8 0

4 years ago

What is the difference between cell and cellmembrane

lisov135 [29]

Answer:

So, a cell, in easiest terms, is "the building blocks of life". Without cells, humans, plants, animals, and anything else that has a cell would not be able to survive. Cells are extremely important to our bodies. Whereas a Cell Membrane is an organelle inside a cell. The Cell Membrane's job is to provide protection for the cell, as well as deciding which substances can enter and exit the cell.

I hope this helps!

3 0

3 years ago

A3. Answer each of the following: A student dissolved 1.3g of Ba(OH)2 (molar mass = 171.34 g/mol) in 250 mL of water and reacted

Sunny_sXe [5.5K]

Answer:

(i) Ba(OH)2 + 2 HNO3 → Ba(NO3)2 + 2 H2O

(ii) 121.392 mL of HNO3 0.125M are required to react completely with the Ba(OH)2 solution.

(iii) The molarity of the Ba(OH)2 solution is 0.0303 M

(iv) Bromothymol Blue (pH range 6.0 - 7.6)

(v) pH of the soultion would be 2.446

Explanation:

(i) First of all, to solve this problem we should write the balanced chemical equation to know the stoichiometry of the reaction:

Ba(OH)2 + HNO3 → Ba(NO3)2 + H2O

The previous reaction simply describes the reactants and products involved in the chemical process. As you can see, the mass balance is not balanced because the quantity of atoms in the reactants side of the equation is not equal to the ones in the products side. So we try to add coefficients to the reaction in order to balance the amount of atoms on both sides of the reaction. To to this, we take a look at the reaction: We see that the main product formed Ba(NO3)2 has 2 atoms of N, so we add a number 2 besides the HNO3 to equal the quantity of Nitrogen atoms:

Ba(OH)2 + 2 HNO3 → Ba(NO3)2 + H2O

Now, we can see that from the reactants side of the equation there are 8 atoms of Oxygen and in the products side we only have 7. Hence, we add the number 2 besides the molecule of water:

Ba(OH)2 + 2 HNO3 → Ba(NO3)2 + 2 H2O

If we check the situation now, we can observe that all the atoms are balanced on both sides of the reaction, so We did it!

(ii) From the balanced equation we now know that 1 mole of Ba(OH)2 reacts with 2 moles of HNO3 to form the stated products. Let's see, therefore, how many moles of Ba(OH)2 are in solution:

According to the molar mass of Ba(OH)2: 1 mole = 171.34 g

So, the student add 1.3 g of the compound to water. This means that he added 7.587x10-3 moles of Ba(OH)2. This amount of Ba(OH)2 will react with 0.01517 moles of HNO3 taking into account the stoichiometry of the balanced equation described above (1 mol of Ba(OH)2 reacts with 2 moles of HNO3).

Now that we know the amount of moles of acid required to react with the hydroxide, we need to translate this moles into volume of acid solution:

We have a 0.125 M HNO3 solution. This means that there are 0.125 moles of HNO3 in 1000 ml of solution.

0.125 moles HNO3 ------ 1000 ml Solution

0.01517 moles --------- x = 121.392 ml HNO3 Solution

This means that we need 121.392 ml of a 0.125 M HNO3 solution to react completely with the Ba(OH)2 added by the student.

(iii) Now we are asked to calculate the molarity of the Ba(OH)2 solution. From the calculations performed before in point (ii) we know that the hydroxide solution consisted of 7.587x10-3 moles of Ba(OH)2 and that this quantity of moles were in 250 mL of water. So:

250 ml Solution ----- 7.587 x10-3 moles Ba(OH)2

1000 ml Solution ----- x = 0.0303 M

(iv) Since Ba(OH)2 and HNO3 are both strong base and acid respectively, they react with each other completely to form the salt Ba(NO3)2 and water. Therefore, the pH of the solution when the reactions ends will be neutral or nearly neutral (pH = 7) and because of this we need an indicator that would change its color around this pH to be able to visualize the end point of the titration. The Bromothymol blue serves this perfectly since its change in color ranges between pH 6.0 and 7.6.

(v) If we now calculate how many moles of HNO3 are present in 150 mL of a 0.125 M solution we obtain:

1000 mL solution ---- 0.125 moles HNO3

150 mL solution ------ x = 0.01875 moles.

From this, we know that if we add 150 mL of the acid solution we would have 0.01875 moles of HNO3. However, from the previous points, we know that 0.01517 moles of the compound will be consumed by the reaction with Ba(OH)2 leaving in solution only 3.58 x10-3 moles of HNO3 (0.01875 moles - 0.01517 moles).

This amount of HNO3 will dissociate according to the following equation:

HNO3 → H+ + NO3-

The amount of protons present in solution will determine the pH. Because, as we said before, Nitric acid is a strong acid, it will dissociate completely intro protons and nitrate. As a result of this, we would have 3.58 x10-3 moles of H+ in the solution (1 mole of HNO3 produces 1 mole of H+) and considering the contribution of protons in the solution given by the dissociation of the water negligible, then:

pH = - log [H+]

pH = - log [3.58 x10-3] = 2.446

3 0

3 years ago

Please helppp I need 1 paragraph I’m about to go to school

kifflom [539]

The data on Climate change is as explained below-

Explanation:

Climate change is the ominous “hard truth” concurrently. However, it is not the first time that climate change is happening. In geological history, we find plenty of evidence of climate change.

The most important and famous of all such changes is the climate change that occurred during the Mesozoic era leading to the extinction of Dinosaurus. The reason behind these all climate changes was different. However, the climate change we are witnessing at present has something extra to all this natural stuff.

The present climate change is fuelled by anthropogenic activities at large. Large scale emission of greenhouse gases possibly from burning of fossil fuels ever since the Industrial revolutions in the late 18th century has altered the chemical composition of atmospheric gases. In addition to the use of fossil fuels other activities such as agriculture, coal-based power plants, deforestation and other such activities have been instrumental in degrading the serene balance between different atmospheric gases.

The evidence of the present climate change can be gauged in-

The rise in global average temperature-Earth’s mean temperature has risen by around 1° C ever since the 19th century. 2017 proved to be the warmest year in the record.
Oceans have been net absorber of the heat. This has led to the warming up of oceans. This severely hampers and impact marine flora and fauna
Deglaciation- the increasing temperature has manifested in the form of shrinking ice-sheets. Large icebergs are calving and thus has some serious long-term impact for the sustenance of mankind.
Rise in the mean sea level- The sea level has risen by almost 10 inches since last century. This increase is all set to increase in future thus endangering the lives and livelihood of the coastal communities.

All the leading personalities of the time including the ex-president of the US Mr Barak Obama emphasised the importance of climate change and urged the global community to tackle it at earliest. In his words, he mentioned, “No other challenge poses as great a threat to the future generation as the climate change”. In addition to Mr Obama, noted climate activist Greta Thunberg described the climate change to be the greatest crisis to the humanity that it has ever faced.

Therefore, it can be safely argued that it’s urgent to talk and act tough on climate change. Climate change has transitioned into a multi-headed monster capable enough to devastate the entire mankind. It has done this earlier and sure to carry it further on.

3 0

3 years ago