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Serga [27]
2 years ago
7

Help anyone? :) please

Chemistry
1 answer:
Elanso [62]2 years ago
8 0

Answer:

6. protons, mass number from the atomic number

7. Li= ,

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FIRST ANSWER = BRAINLIEST
STALIN [3.7K]

A_{r} = 24.3

The average atomic mass of X is the <em>weighted average</em> of the atomic masses of its isotopes.  

We multiply the atomic mass of each isotope by a number representing its <em>relative importance</em> (i.e., its % abundance).  

Thus,  

0.790 × 24 u = 18.96 u

0.100 × 25 u =   2.50 u

0.110 × 26 u =    <u>2.86 u</u>  

       TOTAL =  24.3   u

∴ The relative atomic mass of X is 24.3.


5 0
3 years ago
Hard water often contains dissolved Ca2+ and Mg2+ ions. One way to soften water is to add phosphates. The phosphate ion forms in
avanturin [10]
<span>5.5×10−2M in calcium chloride and 8.0×10−2M in magnesium nitrate.
What mass of sodium phosphate must be added to 1.5L of this solution to completely eliminate the hard water ion

1) Content of Ca (2+) ions

Calcium chloride = CaCl2

Ionization equation: CaCl2 ---> Ca (2+) + 2 Cl (-)

=> Molar ratios: 1 mol of CaCl2 : 1 mol Ca(2+) : 2 mol Cl(-)

Calculate the number of moles of CaCl2 in 1.5 liters of 5.5 * 10^-2 M solution

M = n / V => n = M*V = 5.5 * 10^ -2 M * 1.5 l = 0.0825 mol CaCl2

=> 0.0825 mol Ca(2+)

2) Number of phosphate ions needed to react with 0.0825 mol Ca(2+)

formula of phospahte ion: PO4 (3-)

molar ratio: 2PO4(3-) + 3Ca(2+) = Ca3 (PO4)2

Proportion: 2 mol PO4(3-) / 3 mol Ca(2+) = x / 0.0825 mol Ca(2+)

=> x = 0.0825 coml Ca(2+) * 2 mol PO4(3-) / 3 mol Ca(2+) = 0.055 mol PO4(3-)

3) Content of Mg(2+) ions

Ionization equation: Mg (NO3)2 ----> Mg(2+) + 2 NO3 (-)

Molar ratios: 1 mol Mg(NO3)2 : 1 mol Mg(2+) + 2 mol NO3(-)

number of moles of Mg(NO3)2 in 1.5 liter of 8.0 * 10^-2 M solution

n = M * V = 8.0 * 10^ -2 M * 1.5 liter = 0.12 moles Mg(NO3)2

ions of Mg(2+) = 0.12 mol Mg(NO3)2 * 1 mol Mg(2+) / mol Mg(NO3)2 = 0.12 mol Mg(2+)

4) Number of phosphate ions needed to react with 0.12 mol Mg(2+)

2PO4(3-) + 3Mg(2+) = Mg3(PO4)2

=> 2 mol PO4(3-) / 3 mol Mg(2+) = x / 0.12 mol Mg(2+)

=> x = 0.12 * 2/3 mol PO4(3-) = 0.16 mol PO4(3-)

5) Total number of moles of PO4(3-)

0.055 mol + 0.16 mol = 0.215 mol

6) Sodium phosphate

Sodium phosphate = Na3(PO4)

Na3PO4 ---> 3Na(+) + PO4(3-)

=> 1 mol Na3PO4 : 1 mol PO4(3-)

=> 0.215 mol PO4(3-) : 0.215 mol Na3PO4

mass in grams = number of moles * molar mass

molar mass of Na3 PO4 = 3*23 g/mol + 31 g/mol + 4*16 g/mol = 164 g/mol

=> mass in grams = 0.215 mol * 164 g/mol = 35.26 g

Answer: 35.26 g of sodium phosphate
</span>
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3 years ago
Vehicle emissions devices incorporate a chemical reaction to help control carbon monoxide pollution: 2CO+ O2-&gt;2CO2
BigorU [14]

<em>It convert carbon monoxide faster </em>

3 0
3 years ago
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What is true of a reaction that has reached equilibrium?
BabaBlast [244]

The correct option is A.

A chemical reaction is said to have reached an equilibrium stage if the rate of reaction of the forward reaction is equal to the rate of reaction of the reverse reaction. Two way arrows are usually used to depict equilibrium reactions. These arrows indicate that the chemical reaction can move both ways. At the equilibrium point the concentrations of both the reactants and the products are equal.

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What are the reactants and products when butane combusts with excess oxygen? express your answer as a chemical equation. the equ
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C4H10 + O2 -----> CO2 +H2O
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