Which of the following happens during an endothermic chemical change? (5 points)

what would you be most likely to measure by immsering and object in water and seeing how much the water level rises

Katena32 [7]

Mass, if you know what element you are working with.

4 0

3 years ago

Percentage yield of sodium peroxide if 5 g of sodium oxide produces 5.5 g of sodium peroxide

Rama09 [41]

<h3>Answer:</h3>

87.40 %

<h3>Explanation:</h3>

Concept being tested: Percent yield of a product

We are given;

Mass of Sodium oxide 5 g

Experimental or Actual yield of sodium peroxide IS 5.5 g

We are required to calculate the percent yield of sodium peroxide;

The equation for the reaction that forms sodium peroxide is

2Na₂O + O₂ → 2Na₂O₂

<h3>Step 1; moles of sodium oxide</h3>

Moles = mass ÷ molar mass

Molar mass of sodium oxide is 61.98 g/mol

Therefore;

Moles = 5 g ÷ 61.98 g/mol

= 0.0807 moles

<h3>Step 2: Theoretical moles of sodium peroxide produced </h3>

From the equation, 2 moles of sodium oxide produces 1 mole of sodium peroxide.

Thus, moles of sodium peroxide used is 0.0807 moles

<h3>Step 3: Theoretical mass of sodium peroxide used</h3>

Mass = Number of moles × Molar mass

Molar mass of sodium peroxide = 77.98 g/mol

Therefore;

Theoretical mass = 0.0807 moles × 77.98 g/mol

= 6.293 g

Theoretical mass of Na₂O₂ is 6.293 g

<h3>Step 4: Percent yield of Na₂O₂</h3>

We know that percent yield is given by the ratio of actual yield to theoretical yield expressed as a percentage.

$Percent yield=(\frac{Actual yield}{theoretical yield})100$

$Percent yield(Na_{2}O_{2})=(\frac{5.5g}{6.293g})100$

= 87.40 %

Therefore, the percentage yield of sodium peroxide is 87.4%

8 0

3 years ago

What determines an object’s ability to float?

Nezavi [6.7K]

Simply put, density is how tightly “stuff” is packed into a defined space.

For example, a suitcase jam-packed with clothes and souvenirs has a high density, while the same suitcase containing two pairs of underwear has low density. Size-wise, both suitcases look the same, but their density depends on the relationship between their mass and volume.
Mass is the amount of matter in an object.
Volume is the amount of space that an object takes up in three dimensions.

Density is calculated using the following equation: Density = mass/volume or D = m/v.

If something is heavy for its size, it has a high density. If an object is light for its size it has a low density.

The relative densities of an object and the liquid it is placed in determine whether that object will sink or float.

3 0

2 years ago

A couple is planning to have a child. The father -to-be has six fingers, a dominant trait. His genotype is Ff. His wife has five

Vinvika [58]

A. There’s not enough info

5 0

3 years ago

According to the Arrhenius concept, an acid is a substance that ________. Group of answer choices can accept a pair of electrons

Schach [20]

Answer: an increase in the concentration of $H^+$ in aqueous solutions and is capable of donating one or more $H^+$

Explanation:

According to Arrhenius concept, a base is defined as a substance which donates hydroxide ions $(OH^-)$ when dissolved in water and an acid is defined as a substance which donates hydrogen ions $(H^+)$ in water.

According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

Thus According to the Arrhenius concept, an acid is a substance that causes an increase in the concentration of $H^+$ in aqueous solutions and is capable of donating one or more $H^+$

5 0

3 years ago