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what is cotinental drift defin this term whith three scientific evidnce in 3-5 sentences HELP ME I'LL MAKE YOUR BRAINEST AND YOU

FinnZ [79.3K]

Continental drift is the movement of Earth’s continents over long periods of time. An evidence for this is that some continents look like puzzle pieces that can fit together, such as South America and Africa. Another evidence is that fossils of the same type have been found in different continents, far apart - suggesting that the two continents once were joined. Another evidence is that identical rocks were found at both sides of the Atlantic Ocean by Alfred Wegener, the main developer of the continents drift theory.

4 0

3 years ago

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An ionic bond forms when atoms blank electrons

8_murik_8 [283]

Answer:

An ionic bond forms when atoms transfer electrons.

Explanation:

Ionic bonds are formed when atoms transfer electrons. (In contrast, covalent bonds are formed when atoms share electrons.)

There's a distinction between the two: when two atoms react to form an ionic bond, one atom would completely lose one electron, while the other would completely gain that electron. The atom that loses the electron becomes a positively-charged ion called a cation, whereas the atom that gains the electron becomes a negatively-charged ion called an anion.

For example, consider the reaction between a sodium $\rm Na$ atom and a chlorine $\rm Cl$ atom: $\rm Na + Cl \to NaCl$ .

When the sodium atom and the chlorine atom encounter, the sodium atom would lose one electron to form a positively-charged sodium ion, $\rm Na^{+}$ . The chlorine atom would gain that electron to form a negatively-charged chlorine ion $\rm Cl^{-}$ .

These two ions will readily attract each other because of the opposite electrostatic charges on them. This electrostatic attraction (between two ions of opposite charges) is an ionic bond.

Overall, it would appear as if the sodium $\rm Na$ atom transferred an electron to the chlorine $\rm Cl$ atom to form an ionic bond.

In contrast, when two atoms react to form a covalent bond, they share electrons without giving any away completely. Therefore, it is possible to break certain covalent bonds apart (using a beam of laser, for example) and obtain neutral atoms.

On the other hand, when an ionic bond was broken, the result would be two charged ions- not necessarily two neutral atoms. The electron transfer could not be reversed by simply breaking the bond.

For example, when table salt $\rm NaCl$ is melted (at a very high temperature,) the ionic bond between the sodium ions and chloride ions would (mostly) be broken. However, doing so would only generate a mixture of $\rm Na^{+}$ and $\rm Cl^{-}$ ions- not sodium and chlorine atoms.

7 0

3 years ago

The standard enthalpy change for the following reaction is 656 kJ at 298 K.

tester [92]

Answer:

wasdfgtergfvbr

Explanation:

wdefvgrewfvbgrvredf

3 0

3 years ago

If 13.2 kg of Al 2 O 3 ( s ) , 50.4 kg of NaOH ( l ) , and 50.4 kg of HF ( g ) react completely, how many kilograms of cryolite

Elodia [21]

Answer : The mass of cryolite produced will be, 54.38 kg

Solution : Given,

Mass of $Al_2O_3$ = 13.2 kg = 13200 g

Mass of $NaOH$ = 50.4 kg = 50400 g

Mass of $HF$ = 50.4 kg = 50400 g

Molar mass of $Al_2O_3$ = 101.9 g/mole

Molar mass of $NaOH$ = 40 g/mole

Molar mass of $HF$ = 20 g/mole

Molar mass of $Na_3AlF_6$ = 209.9 g/mole

First we have to calculate the moles of $Al_2O_3,NaOH$ and $HF$ .

$\text{ Moles of }Al_2O_3=\frac{\text{ Mass of }Al_2O_3}{\text{ Molar mass of }Al_2O_3}=\frac{13200g}{101.9g/mole}=129.54moles$

$\text{ Moles of }NaOH=\frac{\text{ Mass of }NaOH}{\text{ Molar mass of }NaOH}=\frac{50400g}{40g/mole}=1260moles$

$\text{ Moles of }HF=\frac{\text{ Mass of }HF}{\text{ Molar mass of }HF}=\frac{50400g}{20g/mole}=2520moles$

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

$Al_2O_3+6NaOH+12HF\rightarrow 2Na_3AlF_6+9H_2O$

From the balanced reaction we conclude that

The mole ratio of $Al_2O_3,NaOH$ and $HF$ is, 1 : 6 : 12

And, the ratio of given moles of $Al_2O_3,NaOH$ and $HF$ is, 129.54 : 1260 : 2520

From this we conclude that, $NaOH,HF$ is an excess reagent because the given moles are greater than the required moles and $Al_2O_3$ is a limiting reagent and it limits the formation of product.