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4 years ago

16 Which change results in the formation of different substances?(1) burning of propane

Chemistry

2 answers:

Fofino [41]4 years ago

8 0

Answer:The correct answer is option (1).

Explanation:

Burning of propane in the presence of oxygen will form carbon-dioxide, water and heat.The chemical reaction can represented as in chemical equation:

$C_3H_8+5O_2\rightarrow 3CO_2+4H_2O+heat$

This is an example of chemical change where new product is formed.

Where as in melting of sold sodium chloride, deposition of carbon-dioxide gas and solidification of water ;phase of the substance is changing that is a physical change is taking place.

Hence, the correct option is (1).

Trava [24]4 years ago

6 0

1. The burning of propane creates different substances: propane and oxygen combine to create water and carbon dioxide:

C3H8 + 5 O2 becomes 3 CO2 + 4 H2O + heat

2. When NaCl melts, it is changing state, but it is still the same NaCl.

3. When gaseous CO2 deposits it is changing state, but it is still the same CO2.

4. When (presumably liquid) water solidifies, it is changing state, but it is still the same water.

So the answer is 1.

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The reaction P4 +502P4010 + 712 kcal is

igor_vitrenko [27]

Answer:

The reaction is exothermic (option 4)

Explanation:

P4 + 5O2 → P4O10 + 712 kcal

In chemical reactions heat can be absorbed or released:

⇒in the first case, when heat is absorbed, this is called an endothermic reaction. The products have more energy than the reactants. The reaction requires or absorbs energy from it's surroundings. That means that in this reaction energy , in the form of heat, will be absorbed by the reactants.

⇒ when heat is released, this is called an exothermic reaction. The reactants have more energy than the products. The reaction gives or releases energy to it's surroundings. That means that in this reaction energy , in the form of heat, will be released by the reactants.

in the case of P4 + 5O2 → P4O10 + 712 kcal

We notice that on the right side, which is the product side, there is a positive amount of energy. This means that the energy is released by the the reactants, in this reaction. The reaction is exothermic.

4 0

3 years ago

Read 2 more answers

What are deltaTb and deltaTf for an aqueous solution that is 1.5g nacl in 0.250kg h2o? Given Kb=0.51 C/m and kr=1.86 C/m

bulgar [2K]

Answer:

$T_f$ for given question is 2.79 and $T_b$ is 0.52

$\Delta T_b = I \times K_b \times m$ {i- vant hoff’s constant ; Kb- constant ; m molarity }

M = no. of moles of the solute present in one kg of solution

Let the weight of amount of solute be “w” and its molecular mass be “M”

Let the mass of the solvent in the given question be “x”

$\Delta T_b = I \times K_b \times (w/M)/ x$

$\Delta T_b = I \times K_b \times w/Mx$

$\Delta T_b = 1 \times 0.51 \times1.5/(0.250 \times 58.44) = 0.052$

$\Delta T_f = M \times K_f = 1.86 \times 1.5 = 2.79$

4 0

3 years ago

1. How many protons does 14/6 C contain? What element is this?

Harman [31]

Answer:

It has 6 protons and its Carbon 14

Explanation:

3 0

3 years ago

HELPP!!!!!!!!!!

muminat

1. Mg + CuSO4 —> MgSO4 + Cu

=> Single displacement reaction

2. 2HCI + Mg(OH)2 —> MgCI2 + H2O

=> Acid - base reaction

3.AgNO3 + NaCI —> AgCI + NaNO3

=> Double displacement reaction

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3 years ago

What starts a convection current in the mantle?

julsineya [31]

Heat in the mantle comes from the Earth's molten outer core, decay of radioactive elements and, in the upper mantle, friction from descending tectonic plates.The temperature difference between the upper and lower boundaries of the mantle requires heat transfer to occur.

Material heating up in the mantle

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2 years ago