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mixas84 [53]
4 years ago
7

some classmates conducted an experiment to find out which brand of paper towels is the strongest. you find out that they didnt t

ry to control any variables write a few sentences explaning why they cannot draw any useful conclusions from their experiment
Chemistry
1 answer:
tamaranim1 [39]4 years ago
5 0
If you do not control your variables, you will not know what affected the results of your experiment. You must only change one variable at a time, and everything else has to remain the same. 
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Calculate ΔH o rxn for the following: CH4(g) + Cl2(g) → CCl4(l) + HCl(g)[unbalanced] ΔH o f [CH4(g)] = −74.87 kJ/mol ΔH o f [CCl
anzhelika [568]

Answer:  ΔH for the reaction is -277.4 kJ

Explanation:

The balanced chemical reaction is,

CH_4(g)+Cl_2(g)\rightarrow CCl_4(l)+HCl(g)

The expression for enthalpy change is,

\Delta H=\sum [n\times \Delta H(products)]-\sum [n\times \Delta H(reactant)]

\Delta H=[(n_{CCl_4}\times \Delta H_{CCl_4})+(n_{HCl}\times B.E_{HCl}) ]-[(n_{CH_4}\times \Delta H_{CH_4})+n_{Cl_2}\times \Delta H_{Cl_2}]

where,

n = number of moles

Now put all the given values in this expression, we get

\Delta H=[(1\times -139)+(1\times -92.31) ]-[(1\times -74.87)+(1\times 121.0]

\Delta H=-277.4kJ

Therefore, the enthalpy change for this reaction is, -277.4 kJ

4 0
3 years ago
What is height? Give an example.
Sav [38]
Height is defined as the distance from the bottom to the top of something or the highest point or the greatest degree. An example of height is 5'8". An example of height is the top of Mount Everest.
5 0
3 years ago
at a given tempature gas with a pressure of 150 kpa has volume of 0.8 l if the pressure decreases to 75kpa and the temperature r
vova2212 [387]
  <span>P*V/T=constant 
so P*V= constant*T 
if T doesn't change then 
P*V= constant 
so 150kPa*0.8L=75kPa*xL 
xL=150kPa*0.8L/75kPa=1.6L 
hope it help</span>
8 0
4 years ago
CO2(g) + H2O(I) - -&gt; C6H12O6(s) + O2(g)
Lana71 [14]

Answer:

For instance equation C6H5C2H5 + O2 = C6H5OH + CO2 + H2O will not be balanced, but PhC2H5 + O2 = PhOH + CO2 + H2O will; Compound states [like (s) (aq) or (g)] are not required. If you do not know what products are enter reagents only and click 'Balance'. In many cases a complete equation will be suggested.

Explanation:

4 0
3 years ago
Sodium Chloride is an ionic compound. Its molar mass is 58.44g. One formula unit of NaCl consists of one____, whose chemical sym
saul85 [17]

Answer: One formula unit of NaCl consists of one cation, whose chemical symbol is Na^+ and one anion whose chemical symbol is Cl^-

Explanation:

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.  

The cation is formed by the metal sodium which forms  Na^+ and the anion is formed by non metal chlorine which forms Cl^-.

For a formula unit of sodium chloride,  the charges have to be balanced , thus the valencies of ions are exchanged and the neutral compound result. Thus

Na^+ and  Cl^- combine to form neutral NaCl

5 0
3 years ago
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