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Leni [432]
3 years ago
11

A blacksmith melts and shapes a block of iron into a blade. She then sets the blade, whose edges are molten, outside, where it i

s raining slightly. The blade's outer edges both solidify and then rust. Which of the following has happened to the iron throughout the day? a. The iron has undergone a physical change only. b. The iron has undergone a chemical change only. c. The iron has undergone both a physical and chemical change. d. The iron has not undergone any changes.
Chemistry
2 answers:
Margaret [11]3 years ago
4 0
The answer is C due to the rain making contact with the iron it creates moisture which cause the iron to begin oxidizing which causes the iron to rust which is a chemical reaction then the blade which was once malleable because it was heat becomes harden and rust is created as I said before the physical aspect of the iron chances due to rust developing on it it's no longer has the luster it once had
ehidna [41]3 years ago
4 0

Answer:

The correct answer is option c.

Explanation:

A physical change is defined as  a change in shape, size takes place. No new substance gets formed in these reactions.

Solid iron block → liquid iron

Liquid iron → solid blade shaped iron

Here, iron in first melted and then set into a shape of blade. Hence, physical change.

A chemical change is defined as a change in chemical composition takes place. A new substance is formed in these reactions.

Here, rusting of iron is chemical change:

Fe(s)+O_2(g)\righarrow Fe_2O_3(s)

Throughout the entire process blacksmith has changed the iron block physically by changing its size and shape. And due to action of raining in the edges of the blade rusting of an iron also took place which was a chemical change.

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Explanation:

chemical analysis of a compound shows that it contains 0.99g lead ,0.154g sulfur and 0.306g oxygen. what is the empirical formula of the compound.

6 0
3 years ago
How many seconds are there in 23 days ?
Brrunno [24]
Since there are 23 days and 24 hours in each day, you multi-ply them and get 552 hours. Since each hours is 60 minutes, 552*60 is 33120 minutes. Since one minute is 60 seconds, 60*33120 is 1,987,200 seconds. Therefore, there are 1,987,200 seconds in 23 days. 
7 0
3 years ago
Metals react with oxygen to give oxides with the general formula MxOy. What is a balanced chemical equation for the reaction of
katovenus [111]

Answer: 4Fe+3O_2\rightarrow 2Fe_2O_3

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.  

Here iron is having an oxidation state of +3 called as Fe^{3+} cation and oxide O^{2-} is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral Fe_2O_3.

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

2Fe+3O_2\rightarrow 2Fe_2O_3

8 0
3 years ago
Read 2 more answers
Activation energy is what kind of chemical reaction that absorbs energy
seraphim [82]

Activation energy is the energy required by reactants to undergo chemical reaction and given products

Every reactant has some internal energy (sum of all kind of energy like kinetic energy, potential energy, mechanical energy, chemical energy etc). It needs some extra energy to undergo chemical reaction which is activation energy

All kinds of reaction whether exothermic or endothermic needs activation energy

Threshold energy = internal energy + activation energy

3 0
3 years ago
A cubic piece of platinum metal (specific heat capacity = 0.1256 J/°C・g) at 200.0°C is dropped into 1.00 L of deuterium oxide ('
polet [3.4K]

Answer:

a=5.65cm

Explanation:

Hello,

In this case, for this heat transfer process in which the heat lost by the hot platinum is gained by the cold deuterium oxide based on the equation:

Q_{Pt}=-Q_{Deu}

We can represent the heats in terms of mass, heat capacities and temperatures:

m_{Pt}Cp_{Pt}(T_f-T_{Pt})=-m_{Deu}Cp_{Deu}(T_f-T_{Deu})

Thus, we solve for the mass of platinum:

m_{Pt}=\frac{-m_{Deu}Cp_{Deu}(T_f-T_{Deu})}{Cp_{Pt}(T_f-T_{Pt})} \\\\m_{Pt}=\frac{-1.00L*1110g/L*4.211J/(g\°C)*(41.9-25.5)\°C}{0.1256J/(g\°C)*(41.9-200.0)\°C} \\\\m_{Pt}=3860.4g

Next, by using the density of platinum we compute the volume:

V_{Pt}=\frac{3860.4g}{21.45g/cm^3}\\ \\V_{Pt}=180cm^3

Which computed in terms of the edge length is:

V=a^3

Therefore, the edge length turns out:

a=\sqrt[3]{180cm^3}\\ \\a=5.65cm

Best regards.

6 0
3 years ago
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