Given :
Mass of gold ( Au ) is 212 gram.
To Find :
Atoms of gold present in 212 gram of gold.
Solution :
Molecular mass of gold is 197 gram.
So, number of moles of gold in 212 gram is :
Now, we know 1 mole of any element contains 
atoms.
So, number of atoms present in 1.076 moles are :
Hence, this is the required solution.
Answer:
endothermic reaction
Explanation:
It simply means that you are witnessing<u> an endothermic reaction</u>.
An endothermic reaction is one that absorbs heat energy from its surrounding, thereby leaving the reaction vessel with a lower temperature as compared to before the reaction.
It is as opposed to exothermic reactions which are reactions that give off energy in the form of heat to the surrounding, thereby leaving a reaction vessel warmer than before the reaction.
<em>In this case, the formation of ice crystals outside the test tube means that heat energy has been absorbed by the reaction which leaves the vessel a temperature cold enough to activate the formation of ice. </em>
Answer:
The answer is Steam is produced when water is heated. The color does not change, a precipice is not formed, and the odor does not change!
Given question is incomplete. The complete question is as follows.
Balance the following equation:
Answer: The balanced chemical equation is as follows.
Explanation:
When a chemical equation contains same number of atoms on both reactant and product side then this equation is known as balanced equation.
For example,
Number of atoms on reactant side:
H = 5
P = 1
O = 6
Ca = 1
Number of atoms on product side:
H = 6
P = 2
O = 9
Ca = 1
In order to balance this equation, we will multiply 
by 2 on reactant side and we will multiply 
by 2 on product side. Hence, the balanced chemical equation is as follows.
First a balanced reaction equation must be established:
→
Now if mass of aluminum = 145 g
the moles of aluminum = (MASS) ÷ (MOLAR MASS) = 145 g ÷ 30 g/mol
= 4.83 mols
Now the mole ratio of Al : O₂ based on the equation is 4 : 3
[
4Al +
3 O₂ → 2 Al₂O₃]
∴ if moles of Al = 4.83 moles
then moles of O₂ = (4.83 mol ÷ 4) × 3
=
3.63 mol (to 2 sig. fig.)
Thus it can be concluded that
3.63 moles of oxygen is needed to react completely with 145 g of aluminum.
