All categories

2 years ago

Social Studies 3rd Period

Chemistry

1 answer:

docker41 [41]2 years ago

7 0

Answer:

The answer is A, B, and D

Explanation:

A: China burned coal more than wood for heat.

B: Marco Polo wrote about a new energy source from China.

D: Marco Polo helped spread technology and ideas all through out Europe.

You might be interested in

Identify the compound with the smallest percent ionic character. identify the compound with the smallest percent ionic character

rosijanka [135]

I'll try. A purely ionic bond, as the name implies is a bond between ions. If that sounds like double-talk it's because some ionic compounds are more ionic than others. A purely covalent compound is one in which the electrons are shared EQUALLY. It turns out that the only compounds in which the electrons are shared equally is one in which both atoms sharing the electrons are of the same element. For example O2, N2, Cl2, I2 or F2. Now suppose you make a compound between Fluorine and Iodine, IF. Since fluorine has a greater attraction for electrons than iodine, the bond will be polar. That is the fluorine part of the molecule will be negative and the iodine part will be positive. The attraction for electrons isn't equal. The same thing happens with ionic bonds. In your first question, the ionic character decreases from NaF through SiF4. Sodium loses an electron quite readily because it achieves a stable neon like configuration. Fluorine attracts an electron very strongly for the same reason. But as you move across the period, two things are happening. First, look at SiF4. Silicon is right in the middle of the period, It can achieve a stable inert gas configuration either by gaining 4 or losing 4 electrons. So it depends upon the electronegativity (the electron grabbing ability) of the atom it's combining with. Since Fluorine has the highest electron grabbing ability of any of the reactive elements, it will tend to pull the electrons away from silicon. But silicon doesn't completely give them up as it would in a purely ionic compound. AlF3 is similar but will tend to give up 3 electrons a little easier than SiF4. MgF2 is even more ionic because it's approaching an inert gas configuration and only need to lose 2 electrons. Can you see what's happening? The closer you get to the middle of a period, the less likely an atom is to give up COMPLETELY its electrons. In question 2 your answer is CO. The elements are close together (which means that their electronic structure is similar) and carbon, like silicon is in the middle of the period so its more likely to share electrons than it is to give them up (form an ionic bond). So it turns out that most chemical bonds are neither completely ionic or covalent but lie in between the two extremes and are called polar covalent. I hope this helps.

4 0

2 years ago

How is data not actually obtained from the experiment represented in a line graph? with a double line with only dots with a colo

Fittoniya [83]

The way how data is not actually obtained from the experiment represented in a line graph is defnitely that a colored line with a broken line. It is a well known fact that to obtain the actual data from the experiment you there should be plotted points on the line. Hope it will help you! Regards.

7 0

2 years ago

Read 2 more answers

How many moles are there in 3.3 grams of NH4SO2

slavikrds [6]

1.69x10 22 molecules

8 0

2 years ago

Iron(II) sulfide reacts with hydrochloric acid according to the reaction:

Inessa [10]

The balanced chemical reaction would be:

FeS(s)+2HCl(aq)→FeCl2(s)+H2S(g)

We are given the amount of the reactants to be used for the reaction. We use these amounts. First, we determine the limiting reactant of the reaction. From the data, we can say that FeS is the limiting ad HCl is the excess reactant. We calculate as follows:

Amount of HCl used: 0.240 mol FeS x 2 mol HCl / 1 mol FeS = 0.48 mol HCl

0.646 - 0.48 = 0.166 mol HCl left

8 0

2 years ago

Read 2 more answers

The amount ofcalcium present in milk can be determined by adding oxalate to asample and measuring the massof calcium oxalate pre

Sauron [17]

Answer: The mass percent of calcium in milk is 0.107 %

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of calcium oxalate = 0.429 g

Molar mass of calcium oxalate = 128.1 g/mol

Putting values in equation 1, we get:

$\text{Moles of calcium oxalate}=\frac{0.429g}{128.1g/mol}=0.0033mol$

The given chemical equation follows:

$Na_2C_2O_4(aq.)+Ca^{2+}(aq.)\rightarrow CaC_2O_4(s)+2Na^+(aq.)$

Sodium oxalate is present in excess. So, it is considered as an excess reagent. And, calcium ion is a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of calcium oxalate is produced from 1 mole of calcium ion

So, 0.0033 moles of calcium oxalate is produced from = $\frac{1}{1}\times 0.0033=0.0033mol$ of calcium ions

Now, calculating the mass of calcium ions by using equation 1, we get:

Moles of calcium ions = 0.0033 moles

Molar mass of calcium ions = 40 g/mol

Putting values in equation 1, we get:

$0.0033mol=\frac{\text{Mass of calcium ions}}{40g/mol}\\\\\text{Mass of calcium ions}=(0.0033mol\times 40g/mol)=0.132g$

To calculate the mass percentage of calcium ions in milk, we use the equation:

$\text{Mass percent of calcium ions}=\frac{\text{Mass of calcium ions}}{\text{Mass of milk}}\times 100$

Mass of milk = 125 g

Mass of calcium ions = 0.132 g

Putting values in above equation, we get:

$\text{Mass percent of calcium ions}=\frac{0.132g}{125g}\times 100=0.107\%$

Hence, the mass percent of calcium in milk is 0.107 %

7 0

2 years ago