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Travka [436]
2 years ago
7

can someone help me with these? I just started chemistry this semester, and since it's involving math I don't see myself doing g

ood.

Chemistry
1 answer:
V125BC [204]2 years ago
4 0

Any non zero digits are significant. (120 has 2 sig figs)

Zeroes between significant digits are significant. (103 has 3 sig figs)

Zeroes only count if there is a decimal point and if they are following a significant digit. (.600 has 3 sig figs; .067 has 2 sig figs)

1) <u>1278.50</u> = 6 sig figs

2) <u>12</u>0000 = 2 sig figs

3) <u>90027.00</u> = 7 sig figs

4) 0.00<u>53567</u> = 5 sig figs

5) <u>67</u>0 = 2 sig figs

6) 0.00<u>730</u> = 3 sig figs

That's all I'm gonna do so yeah.

Now for the rounding, it's basically rounding but it must have the x amount of sig figs after rounding. It's pretty hard to explain.

19, I'm not really sure. Might be 120 with a decimal point at the end.

20) 5.457, alright so here, since we are rounding to three significant digits, we look at the third sig fig. The third sig fig here would be 5. Then we just round. Since the number next to 5 is 7, we round 5 up to 6.

So 5.457 rounded to 3 sig figs would be 5.46

21) 0.0008769, the third sig fig here would be 6. You round 6 up to 7 because the number next to it is 9.

So 0.0008769 rounded to 3 sig figs would be 0.000877

So I hope you get it, I'm gonna let you do the rest.

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Which root word of the binary ionic compound ends with -ide
kondor19780726 [428]

Answer: C. The non metal

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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.

The nomenclature of ionic compounds is given by:

1. Positive ion or metal is written first.

2. The negative ion or non metal is written next and a suffix is added at the end of the negative ion. The suffix written is '-ide'.

For example: CsBr , cesium is metal having an oxidation state of +1 called as Cs^{+} cation and bromine Br^{-} is an anion with oxidation state of -1. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral CsBr called as cesium bromide.

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For a particular isomer of C 8 H 18 , the combustion reaction produces 5099.5 kJ of heat per mole of C 8 H 18 ( g ) consumed, un
xz_007 [3.2K]

Answer:

the standard enthalpy of formation of this isomer of C₈H₁₈ (g) =  -375 kj/mol

Explanation:

The given combustion reaction

C₈H₁₈ + 25/2 O₂ → 8 CO₂ + 9 H₂O   ............................(1)

Heat of reaction or enthalpy of combustion = -5099.5 kj/mol

from equation (1)

     ΔH⁰reaction = (Enthalpy of formation of products - Enthalpy of formation                    of reactants)

Or,     - 5099.5   = [8 x ΔH⁰f(CO₂) +9 x ΔH⁰f(H₂O)] - [ΔH⁰f(C₈H₁₈) + ΔH⁰f(O₂)].................................(2)

Given ΔH⁰f(CO₂) = - 393.5 kj/mol  & ΔH⁰f(H₂O) = - 285.8 kj/mol and ΔH⁰f(O₂)= 0

Using equation (2)

ΔH⁰f(C₈H₁₈) = -621 kj/mol

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3 years ago
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