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Paul [167]
4 years ago
9

-3 × 4=? ....................​

Chemistry
2 answers:
blagie [28]4 years ago
8 0

Answer:

-12

Explanation:

a negative times a positive is negative

e-lub [12.9K]4 years ago
5 0
-12 ...................
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Using the balanced equation for the combustion of ethane: 2C2H6 + 7O2 → 4CO2 + 6H2O, how many moles of O2 needed to produce 12 m
pickupchik [31]

Answer:

14 moles of oxygen needed to produce 12 moles of H2O.

Explanation:

We are given that balance eqaution

2C_2H_6+7O_2\rightarrow 4CO_2+6H_2O

We have to find number of moles of O2 needed  to produce 12 moles of H2O.

From given equation

We can see that

6 moles of   H2O produced by Oxygen =7 moles

1 mole of   H2O produced by Oxygen=\frac{7}{6}moles

12 moles of H2O produced by Oxygen=\frac{7}{6}\times 12moles

12 moles of H2O produced by Oxygen=7\times 2moles

12 moles of H2O produced by Oxygen=14 moles

Hence, 14 moles of oxygen needed to produce 12 moles of H2O.

3 0
3 years ago
The Lucas test has _______ results based on the type of alcohol present because the reaction involves a _________, which is ____
Olin [163]

Answer:

1) positive

2) carbocation

3) most stable

4) faster

Explanation:

A common test for the presence of alcohols can be achieved using the Lucas reagent. Lucas reagent is a mixture of concentrated hydrochloric acid and zinc chloride.

The reaction of Lucas reagent reacts with alcohols leading to the formation of an alkyl chloride. Since the reaction proceeds via a carbocation mechanism, tertiary alcohols give an immediate reaction. Once a tertiary alcohol is mixed with Lucas reagent, the solution turns cloudy almost immediately indicating an instant positive reaction.

Secondary alcohols may turn cloudy within five minutes of mixing the solutions. Primary alcohols do not significantly react with Lucas reagent obviously because they do not form stable carbocations.

Therefore we can use the Lucas reagent to distinguish between primary, secondary and tertiary alcohols.

5 0
4 years ago
You have a 15.0 gram sample of gold at 20.0°C. How much heat does it take to raise the temperature to 100.0°C?
Nadusha1986 [10]

Answer:

=154.8 J

Explanation:

The rise in temperature is contributed by the change in temperature.

Change in enthalpy = MC∅,  where M is the mass of the substance, C is the specific heat capacity and ∅ is the change in temperature.

Change in temperature = 100.0°C-20.0°C=80°C

ΔH=MC∅

The specific heat capacity of gold= 0.129 J/g°C

ΔH= 15.0g×0.129J/g°C×80°C

=154.8 J

7 0
3 years ago
Calculate the molecular weight of a substance. In which the solution of this substance in the water has a concentration of 7 per
Eduardwww [97]

Answer : The molecular weight of a substance is 157.3 g/mol

Explanation :

As we are given that 7 % by weight that means 7 grams of solute present in 100 grams of solution.

Mass of solute = 7 g

Mass of solution = 100 g

Mass of solvent = 100 - 7 = 93 g

Formula used :  

\Delta T_f=i\times K_f\times m\\\\T_f^o-T_f=k_f\times\frac{\text{Mass of substance(solute)}\times 1000}{\text{Molar mass of substance(solute)}\times \text{Mass of water(solvent)}}

where,

\Delta T_f = change in freezing point

T_f^o = temperature of pure water = 0^oC

T_f = temperature of solution = -0.89^oC

K_f = freezing point constant of water = 1.86^oC/m

m = molality

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

(0-(-0.89))^oC=1.86^oC/m\times \frac{7g\times 1000}{\text{Molar mass of substance(solute)}\times 93g}

\text{Molar mass of substance(solute)}=157.3g/mol

Therefore, the molecular weight of a substance is 157.3 g/mol

7 0
3 years ago
Please help<br> What are 4 examples of ionically bonded compounds?
frez [133]
Ionic compounds generally occur between metals and non-metals due to their large electronegativity difference. You can simple go down Group 1 and Group 17 of the periodic table.

Examples:

NaCl (Sodium Chloride)
KCl (Potassium Chloride)
RbCl (Rubidium Chloride)
CsCl (Cesium Chloride)
8 0
3 years ago
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