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2 years ago

Is fireworks a physical or a chemical change and why??

Chemistry

1 answer:

Elanso [62]2 years ago

7 0

Answer:

fireworks is a chemical change

Explanation:

Because during a chemical change, substances are changed into different substances. In different terms, the composition of the substance changes.

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URGENT PLEASE HELP!!

Orlov [11]

Answer:

Liters per second is 0.2 LPS

Liters per hour is 720

Explanation:

Divide the litres by the time, than multiply the time of an hour (in seconds) and than multiply the lps by time of an hour in seconds.

3 0

3 years ago

The proposed mechanism for a reaction is 1. ClO-(aq) + H2O(l) => HClO(aq) + OH-(aq) SLOW 2. I-(aq) + HClO(aq) => HIO(aq) +

HACTEHA [7]

Answer:

The correct answer is option A.

Explanation:

Step 1 : Slow

$ClO^-(aq) + H_2O(l)\rightarrow HClO(aq) + OH^-(aq)$

Step 2: Fast

$I^-(aq) + HClO(aq)\rightarrow HIO(aq) + Cl^-(aq)$

Step 3: Fast

$OH^-(aq) + HIO(aq)\rightarrow H_2O(l) + IO^-(aq)$

When there is a recation which is taking place in a more that single steps than the rate of the reaction is determined by the slowest step occurring in the reaction mechanism.

So, according to question step 1 is slow step which means that rate of the reaction will be :

$R=k[ClO^-][H_2O]$

8 0

3 years ago

Calculate the pH of: (a) 0.1M HCl; (b) 0.1M NaOH; (c) 3 X 10% M HNO3; (d) 5 X 10-10 M HCIO.; and (e) 2 x 10-8 M KOH.

Shtirlitz [24]

Answer:

(a) $pH = -Log (0.1M) = 1$

(b) $pH = -Log (10^{-13}M) = 13$

(d) $pH = -Log (4.93x10^{-10}M) = 9.3$

(e) $pH = -Log (5^{-7}M) = 6.3$

Explanation:

To calculate de pH of an acid solution the formula is:

$pH = -Log ([H^{+}]) = 1$

were [H^{+}] is the concentration of protons of the solution. Therefore it is necessary to know the concentration of the protons for every solution in order to solve the problem.

(a) and (c) are strong acids so they dissociate completely in aqueous solution. Thus, the concentration of the acid is the same as the protons.

(b) and (e) are strong bases so they dissociate completely in aqueous solution too. Thus, the concentration of the base is the same as the oxydriles. But in this case it is necessary to consider the water autoionization to calculate the protons concentration:

$K_{w} =[H^{+} ][OH^{-}]=10^{-14}$

clearing the $[H^{+} ]$

$[H^{+} ]=\frac{10^{-14}}{[OH^{-}]}$

(d) is a weak base so it is necessary to solve the equilibrium first, knowing $Ka=3.24x10^{-8}$

The reaction is $HClO$ → $H^{+} + CO^{-}$ so the equilibrium is

$Ka=3.24x10^{-8}=\frac{x^{2}}{5x10^{-8}-x}$

clearing the <em>x</em>

${x^{2}={1.62x10^{-17}-3.24x10^{-8}x}$

$x=[H^{+}]=4.93x10^{-10}$

6 0

4 years ago

The amount of thermal energy stored in an object depends on what

Snowcat [4.5K]

Answer:

The amount of thermal energy stored in an object depends on three things.

The mass of the object.
The temperature of the object.
The amount of energy that the particular material stores per degree of temperature.

3 0

3 years ago

Read 2 more answers

What is the molecular formula for se?

patriot [66]

A chemical formula that shows the total number and kinds of atoms in a molecule, but not their structural arrangement. For example, the molecular formulaof aspirin is C9H8O4

8 0

4 years ago