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3 years ago

How do you tell by the formula that an element on the periodic table is a metal

1 answer:

7 0

The metalloids are on the right side of the periodic table B, Si, Ge, As, Sb, Te, and At. The nonmetals are also on the right side next to the metalloids, there should be a He at the top right of the periodic table and there should be one more nonmetal at the top left of the periodic table that is H. And from the metals they are all on the middle next to the metalloids, starting from Li, Be, Na, and Mg as so on all of those are metals.

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How is it that when a salt sample dissolves in water, the delta S for the process is positive?

Bess [88]

Answer:-

Water is highly ordered. In water each oxygen atom is connected to others around it through hydrogen bonding via bridging hydrogen atoms. When a salt like NaCl is dissolved, some of these Hydrogen bonds break.

When a salt like NaCl dissolves in water, the NaCl breaks in to ions Na+ and Cl-.

The water molecules now surround these ions.

The slightly negative oxygen end of water molecule gets near the Na+, while the slightly positive Hydrogen of water molecule gets near the Cl-.

So before salt sample dissolve, the water molecules were highly ordered due to hydrogen bonding. Now after salt dissolve there is a decrease in order and thus an increase in disorder of the water molecules.

Due to increase in disorder, entropy which is a measure of disorder increases. Since entropy increases, delta S for the process is positive.

4 0

3 years ago

If an atom has a mass number of 23, which of the following is always true?

lesantik [10]

Atomic number is less than 11

8 0

2 years ago

You need 455 ml of a 75% alcohol solution. on hand, you have a 25% alcohol mixture. you also have a 90% alcohol mixture. how muc

marishachu [46]

X ml - <span>25% alcohol mixture
y ml - </span><span>90% alcohol mixture

x+y = 455

0.25x ml alcohol in </span>x ml of 25% alcohol mixture
0.9y ml alcohol in y ml of  90% alcohol mixture
0.75*455= 341.25 ml alcohol in 455 ml of  75% alcohol mixture

0.25x+0.9y=341.25

System of equations:

x+y = 455 /*(-0.25) ------> -0.25x-0.25y = -0.25*455
0.25x+0.9y=341.25

-0.25x-0.25y=-113.75
0.25x+0.9y=341.25 Add both equations

0.25x+0.9y-0.25x-0.25y=341.25-113.75
0.65y =227.5
y=227.5/0.65 = 350 ml  of  90% alcohol mixture

x+y=455
x+355=455
x=100 ml of  25% alcohol mixture

8 0

3 years ago

14. 60. g of NaOH is dissolved in enough distilled water to make 300 mL of a stock solution. What volumes of this solution and d

zepelin [54]

The question is incomplete, the complete question is attached below.

Answer : The volumes of stock solution and distilled water will be, 20 mL and 80 mL respectively.

Explanation : Given,

Mass of NaOH = 60 g

Volume of stock solution = 300 mL

Molar mass of NaOH = 40 g/mol

First we have to calculate the molarity of stock solution.

$\text{Molarity}=\frac{\text{Mass of }NaOH\times 1000}{\text{Molar mass of }NaOH\times \text{Volume of solution (in mL)}}$

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

$\text{Molarity}=\frac{60g\times 1000}{40g/mole\times 300mL}=5mole/L=5M$

Now we have to determine the volume of stock solution and distilled water mixed.

Formula used :

$M_1V_1=M_2V_2$

where,

$M_1\text{ and }V_1$ are the molarity and volume of stock solution.

$M_2\text{ and }V_2$ are the molarity and volume of diluted solution.

From data (A) :

$M_1=5M\\V_1=20mL\\M_2=1M\\V_2=?$

Putting values in above equation, we get:

$5M\times 20mL=1M\times V_2\\\\V_2=100mL$

Volume of stock solution = 20 mL

Volume of distilled water = 100 mL - 20 mL = 80 mL

From data (B) :

$M_1=5M\\V_1=20mL\\M_2=1M\\V_2=?$

Putting values in above equation, we get:

$5M\times 20mL=1M\times V_2\\\\V_2=100mL$

Volume of stock solution = 20 mL

Volume of distilled water = 100 mL - 20 mL = 80 mL

From data (C) :

$M_1=5M\\V_1=60mL\\M_2=1M\\V_2=?$

Putting values in above equation, we get:

$5M\times 60mL=1M\times V_2\\\\V_2=300mL$

Volume of stock solution = 60 mL

Volume of distilled water = 300 mL - 60 mL = 240 mL

From data (D) :

$M_1=5M\\V_1=20mL\\M_2=1M\\V_2=?$

Putting values in above equation, we get:

$5M\times 60mL=1M\times V_2\\\\V_2=300mL$

Volume of stock solution = 60 mL

Volume of distilled water = 300 mL - 60 mL = 240 mL

From this we conclude that, when 20 mL stock solution and 80 mL distilled water mixed then it will result in a solution that is approximately 1 M NaOH.

Hence, the volumes of stock solution and distilled water will be, 20 mL and 80 mL respectively.

5 0

3 years ago

Which valid empercal formula below would have one. Five times as much oxygen as there is gold in the substance

stealth61 [152]

Answer:

Au2O3

Explanation:

See attachment.

3 0

2 years ago