Answer:
Na₂CO₃.2H₂O
Explanation:
For the hydrated compound, let us denote is by Na₂CO₃.xH₂O
The unknown is the value of x which is the amount of water of crystallisation.
Given values:
Starting mass of hydrate i.e Na₂CO₃.xH₂O = 4.31g
Mass after heating (Na₂CO₃) = 3.22g
Mass of the water of crystallisation = (4.31-3.22)g = 1.09g
To determine the integer x, we find the number of moles of the anhydrous Na₂CO₃ and that of the water of crystallisation:
Number of moles = 
Molar mass of Na₂CO₃ =[(23x2) + 12 + (16x3)] = 106gmol⁻¹
Molar mass of H₂O = [(1x2) + (16)] = 18gmol⁻¹
Number of moles of Na₂CO₃ = 
= 0.03mole
Number of moles of H₂O = 
= 0.06mole
From the obtained number of moles:
Na₂CO₃ H₂O
0.03 0.06
Simplest
Ratio 0.03/0.03 0.03/0.06
1 2
Therefore, x = 2
Answer:
A 03
Explanation:
jammer as verkeerd
Ek is nog steeds 'n beginner
<span>I did some investigation and summarized the process and made a clearer explanation so those who are confused can imagine the process better :) A scientific theory attempts to explain and describe why things happen. Hypotheses are formed and experiments are done to validate or toss the hypothesis based on the data collected. The Atomic Theory has gone through lots of refining as a scientific theory. For instance, William Crookes conduced an experiment with cathode ray tubes powered by electricity that glowed when powered. Crookes placed an object in between the positive and negative electrode and concluded that the shadow made on the positive side was small particles of matter traveling from the negative side. But more evidence was needed so, later on, J.J. Thomson continued Crookes experiment. He tested what would happen if a negative or positive charged rod was placed along the ray tubes and if it would differ if a different element was used as the negative electrode. Thomson found out that the beam had negatively charged particles and that even if the negative electrode is substituted, the glow is still present, meaning that all elements also had the small negative particles. These particles(now known as electrons) were smaller than the atom and were added to the model of the atom dispersed throughout the neutrally charged atom inside its positive sphere. Now came along Rutherford hoping to support Thomsons model by firing positively charged particles at a thin gold foil thinking it would go straight through the foil, but instead it evenly distributed as they went through the foil, concluding that atoms have a small, dense nucleus(containing positive protons and most of the mass of the atom) that deflected the particles passing through. This was a drastic change in the model now knowing that 1 proton has 2000 times the mass of an electron, but its positive charge cancels the negative electron. After WW1, Chadwick and others were seeing that sometimes the mass of the atom was greater than the mass of the protons and the number of protons was less than the mass of the atom. So it was thought that there were extra electrons and protons adding mass in the nucleus but cancelling their charges, but Rutherford proposed a particle with mass but no charge and called it a neutron; made of paired protons and electrons. But scientists kept studying atoms since there was no evidence of the neutron. Chadwick repeated these experiments though, in hopes to find the neutron and succeeded in 1932, finding it in the nucleus with a close mass to the proton. Thanks to these experiments for refining a scientific theory, we now have a clearer model of the atom.</span>
Answer:
54 grams ammonium chloride and 40 grams sodium hydroxide
Explanation:
A buffer is a solution that contains either a weak acid and its salt or a weak base and its salt, the solution is resistant to changes in pH. This means that, a buffer is an aqueous solution of either a weak acid and its conjugate base or a weak base and its conjugate acid.
A Buffer is used to maintain a stable pH in a solution, buffers can neutralize small quantities of additional acid of base. For any buffer solution, there is always a working pH range and a set amount of acid or base that can be neutralized before the pH will change. The amount of acid or base that can be added to a buffer before changing its pH is called its buffer capacity.
A good buffer mixture is supposed to have about equal concentrations of its both components. It is a rule of thumb therefore, that a buffer solution has generally lost its usefulness when one component of the buffer pair is less than about 10% of the other component.
The implication of this is that the ammonium chloride and sodium hydroxide should be of approximately the same concentration. If the masses are dissolved as shown in the answer, then we will have 1molL-1 of each component of the buffer in accordance with the rule of thumb stated above.
Answer:
207g
Explanation:
Given compound:
Ca(ClO₃)₂
The equivalent mass can be derived by summing the molar masses of each atom
Molar mass of Ca = 40
Cl = 35.5
O = 16
Now solve;
Molar mass = 40 + 2(35.5 + 3(16)) = 207g
