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3 years ago

7

A speed time graph shows that a car moves at 20 m/s for 15s. The car's speed steadily decreases until it comes to a stop at 40s.

Which of the following describes the slope of the speed time graph from 15s to 40s

1 answer:

ladessa [460]3 years ago

4 0

0s to 15s: constant speed/zero acceleration
15s to 40s: constant gradient, therefore constant deceleration

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Using the example in the above information determine the empirical formula of a compound if a sample contains 0.130 g of nitroge

olga2289 [7]

Answer: The empirical formula for the given compound is $NO_2$

Explanation : Given,

Mass of O = 0.370 g

Mass of N = 0.130 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{0.370g}{16g/mole}=0.0231moles$

Moles of Nitrogen = $\frac{\text{Given mass of nitrogen}}{\text{Molar mass of nitrogen}}=\frac{0.130g}{14g/mole}=0.00928moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.00928 moles.

For Oxygen = $\frac{0.0231}{0.00928}=2.4\approx 2$

For Nitrogen = $\frac{0.00928}{0.00928}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of O : N = 2 : 1

Hence, the empirical formula for the given compound is $NO_2$

4 0

3 years ago

When balancing a chemical equation, what are the large numbers that we adjust?

Nata [24]

Answer:

Coefficients

Explanation:

Chemical equations are first written as a skeleton equation, which includes how many atoms each element and compound has. Skeleton equations are not 'balanced' because the number of atoms of each element on the left side (reactants) is not equal to the right side (products).

To balance a chemical equation, you can write coefficients in front of single elements and compounds. The coefficient multiplies with each single element and with each element in the compound.

For example, in this skeleton equation:

H₂ + Cl₂ => HCl

Reactants: Products:

2 hydrogen 1 hydrogen

2 chlorine 1 chlorine

Write the coefficient 2 in the products.

H₂ + Cl₂ => 2HCl

Now both reactant and product sides have 2 chlorine and 2 hydrogen, so the equation is balanced.

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3 years ago

Which color changes represent a positive reaction for the presence of starch using the iodine test?

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Looking at a ph level color chart, it should be moving to more acidic if it’s positive

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3 years ago

Calculate the molecular formula of a compound with the empirical formula C5H11 and a molar mass of 142.32 grams/mole

MA_775_DIABLO [31]

Relative formula mass C₅H₁₁ = 71

Now divide the molar mass by the RFM = 142.32 / 71 = 2

Now C₍₅ₓ₂₎H₍₁₁ₓ₂) = C₁₀H₂₂

Hope that helps

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3 years ago

2. What ions are present in what ratio in a solution of aqueous calcium chloride?

Alenkasestr [34]

Answer:

$\mathrm{Ca}^{2+} \text { and } \mathrm{Cl} \text { - ions are present in } 1: 2 \text { ratio in a solution of aqueous calcium chloride. }$

Explanation:

Here in Calcium Chloride ionic bond is present in between calcium and chlorine atoms. As we know according to Octet rule calcium have two excess atoms and for matching nearest noble gas electronic configuration. It donate two electrons to gain more stability and form $\mathrm{Ca}^{2+}$ , while chlorine is deficient from one electron to meet nearest noble gas electronic configuration therefore two chlorine atoms accept excess electron from calcium individually and form two $\mathrm{Cl}^{-}$ ions.

$\text { Equation is as follows: } \mathrm{Ca}^{2+}+2 \mathrm{Cl}^{-} \rightarrow \mathrm{CaCl}_{2}$

Hence aqueous solution of calcium chloride breaks the ionic bond pairing in one $\mathrm{Ca}^{2+}$ and two $\mathrm{Cl}^{-}$ ions: $\mathrm{CaCl}_{2} \longrightarrow \mathrm{H}_{2} \mathrm{O} \quad \mathrm{Ca}^{2+}(\mathrm{ag})+2 \mathrm{Cl}(\mathrm{ag})$

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3 years ago