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2 years ago

Match these items :))))))

Chemistry

1 answer:

Phoenix [80]2 years ago

3 0

1. Evaporation, 2. Reactants, 3. Gamma rays, 4. Rusting, 5. 0 degrees c, 6. Oxidation, 7. Nuclear, 8. Fusion, 9. Burning, 10. Thermo.

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3 years ago

13. How many moles of zinc are in 25.00 g Zn?

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0.3824 moles of Zinc

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3 years ago

An object should float in a liquid if it is

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Less dense than the liquid

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2 years ago

Calculate the pH of the solution that results when 20 mL of 0.2M HCOOH is mixed with 25mL of 0.2M NaOH solution.(post-equivalenc

Paul [167]

The pH of the solution : 12

<h3>Further explanation</h3>

Reaction

HCOOH + NaOH ⇒ HCOONa + H₂O

mol HCOOH =

$\tt 20~ml\times 0.2~M=4~mlmol$

mol NaOH =

$\tt 25~ml\times 0.2~M=5~mlmol$

Mol NaOH>mol HCOOH ⇒ at the end of the reaction there will be a strong base remains from mol NaOH, so that the pH is determined from [OH⁻]

ICE method :

HCOOH + NaOH ⇒ HCOONa + H₂O

4 5

4 4 4 4

0 1 1 1

Concentration of [OH⁻] from NaOH :

$\tt \dfrac{1~mlmol}{20+25~ml}=0.02$

pOH=-log[OH⁻]

pOH=-log 10⁻²=2

pH+pOH=14

pH=14-2=12

3 0

3 years ago

This is the chemical formula for talc Mg3(Si2O5)2(OH)2(the main ingredient in talcum powder):

Elena-2011 [213]

Answer:

0.022 mol O

Explanation:

Mg3(Si2O5)2(OH)2

We can see that 1 mol of this substance has 3 mol of Mg.

Oxygen altogether is 5*2 (from (Si2O5)2) + 2(from(OH)2) = 10 +2 = 12

So, 1 mol of this substance has 12 mol oxygen.

So, 1 mol of this substance contains 3 mol Mg and 12 mol O, or

ratio Mg : O = 3 : 12 = 1 : 4

1 mol Mg ----- 4 mol O

0.055 mol Mg ---x mol O

x = 0.055*4/1 = 0.220 mol O

8 0

3 years ago