Question

What is always true of a combustion reaction?

Oxygen gas must be one of the reactants
Carbon monoxide will be produced
The reaction absorbs energy
One reactant must contain chlorine

Answer 1

can some please answerthis thanks

Answer 2

@iambatman @myininaya

Answer 3

@dan815 @vera_ewing

Answer 4

@zepdrix @Haseeb96

Answer 5

The reactants of a combustion reaction are a fuel oxygen gas. When the fuel is organic the products are carbon dioxide and water. The reaction releases heat (energy).

Answer 6

@peachpi what would choice be

Answer 7

Carbon monoxide is the result of incomplete combustion, a combustion reaction where there's a lack of oxygen

Answer 8

Oxygen gas must be one of the reactants for this reaction to happen.

Answer 9

can you do this ? @photon336
Which answer best completes the sentence below?

An example of a physical property is _____, while an example of a chemical property is _____.

mass, volume
color, boiling point
density, reactivity
flammability, length

Answer 10

The way I understand it is that a Chemical property is one at the molecular level where the bonds are broken and formed to result in a new compound or substance, and its identity is changed.

I believe density and reactivity are the best choices. reactivity is just as it implies, how something will react, that's definitely a chemical property,

Answer 11

okay what about this If the reaction of 3.50 moles of lithium with excess hydrofluoric acid was able to produce 1.32 mol H2, what is the precent yield of the reaction?

Unbalanced equation: Li + HF yields LiF + H2

75.4%
37.7%
18.9%
13.3%

Answer 12

@Photon336

Answer 13

Do you know how to balance the equation?

Answer 14

alittle but but would the answer b the second choice ?

Answer 15

Let's first balance it \[2Li + 2Hf --> 2LIF +H2\]

Answer 16

Count the number of atoms on both sides, you see in the unbalanced you have 2 atoms of hydrogen on one side and one atom on the other so you multiply by two.

Answer 17

Li + HF yields LiF + H2

Answer 18

=2 Li + 2 HF = 2 LiF + H2

Answer 19

@Photon336

Answer 20

We know that HF is in excess so to do the calculation we need to use the limiting reagent the one that runs out in our case that's lithium.

The molar ratio is 2:1 so we should theoretically get

3.50 li x (H2/2Li) = 1.75 mol of H2 from the equation.

What we actually get is 1.32

So it's what you get form experiment over stiochiometry

1.32/1.75

Answer 21

And that's 75.4%

Answer 22

Does this make sense how I got it, you always have to balance your equation before you do any calculation

Answer 23

yes

Answer 24

okay what about this u know the answr? Which of the following is a double replacement reaction?

K2S + CoCl2 yields 2KCl + CoS
Ca + 2H2O yields Ca(OH)2 + H2
CaO + H2O yields Ca(OH)2
2KClO3 yields 2KCl + 3O2

Answer 25

@Photon336

Answer 26

Here's what happens in a double replacement reaction:

AB + CD ---> AC + BD

see what happened?

Answer 27

ya so it would b c

Answer 28

2KClO3 ---> 2KCL + 3O2 this is a decomposition reaction general formula:

A----> B + C

CaO + HOH ----> Ca(OH)2 this isn't double replacement either.

Answer 29

so d would be the answer?

Answer 30

@Photon336

Answer 31

K2S + CoCl2 ---> 2KCl + CoS that's your double replacement reaction.

Potassium K reacts with Cl and Co reacts with sulfur.

Follows the formula I showed you earlier.

Answer 32

Can you see why it's a?

Answer 33

yes

Answer 34

@Photon336 Can you please help me with my question?