Answer:
C
Explanation:
no. of moles = no. of atoms/ Avogadro's number
0.5= N/6.02×10^23
N= 3.01×10^23
The question is incomplete, the complete question is;
The table above summarizes data given to a student to evaluate the type of change that took place when substance X was mixed with water. The student claimed that the data did not provide enough evidence to determine whether a chemical or physical change took place and that additional tests were needed. Which of the following identifies the best way to gather evidence to support the type of change that occurred when water and Xwere mixed?
A. Measuring the melting point of the mixture of water and X
B. Adding another substance to the mixture of water and X to see whether a solid forms
C Measuring and comparing the masses of the water, X, and the mixture of water and X
D Measuring the electrical conductivities of X and the mixture of water and X
Answer:
D Measuring the electrical conductivities of X and the mixture of water and X
Explanation:
Unfortunately, I am unable to reproduce the table here. However, from the table, the temperature of the of the mixture of the solid X and water was 101.6°C. This is above the boiling point of water and way below the temperature of the solid X.
This goes a long way to suggest that there was some kind of interaction between the water and X which accounted for the observed temperature of the system of X in water.
The only way we can be able to confirm if X actually dissolved in water is to measure the conductivity of the water. dissolved solids increase the conductivity of water.
Sedimentary rock can be minazute by adding more heat n pressure
the balanced chemical equation for decomposition of HgO is as follows
2HgO --> 2Hg + O₂
stoichiometry of HgO to O₂ is 2:1
number of HgO moles heated are - 3.00 g / 216.59 g/mol = 0.0139 mol
according to stoichiometry of reaction -
number of O₂ moles formed = 0.0139 mol/ 2 = 0.00695 mol
mass of O₂ to be formed - 0.00695 mol x 32.00 g/mol = 0.2224 g
but the actual yield = 0.195 g
percent yield = actual yield / theoretical yield x 100 %
percent yield = 0.195 g / 0.2224 g x 100 % = 87.7 %
answer is 87.7 %
Answer:
n NaHCO3 = 9.6 E-3 mol
Explanation:
balanced reaction:
- 2 NaHCO3(s) + H2SO4(ac) ↔ Na2SO4(ac) + 2 CO2(g) + 2 H2O(l)
- assuming a concentration of H2SO4 6M....normally worked in the lab
⇒ n H2SO4 = 8 E-4 L * 6 mol/L = 4.8 E-3 mol H2SO4
according to balanced reaction, we have that for every mol of H2SO4 there are two mol of NaHCO3 ( sodium bicarbonate)
⇒ mol NaHCO3 = 4.8 E-3 mol H2SO4 * ( 2 mol NaHCO3 / mol H2SO4 )
⇒ ,mol NaHCO3 = 9.6 E-3 mol
So 9.6 E-3 mol NaHCO3, are the minimun moles necessary to neutralize the acid.
