Answer :
Sand is composed primarily of silicon dioxide (SiO2). The question states that a grain of sand has approximately 1.69x10* moles of SiO2. To determine the weight of a grain of sand in grams, we can use the molar mass of SiO2.
The molar mass of SiO2 is 60.08 g/mol (28.08 g/mol for Si + 32.00 g/mol for O). Since a grain of sand is composed entirely of SiO2, we can use this molar mass to convert moles to grams.
First, we calculate the number of grams of SiO2 in 1.69x10× moles:
1.69x10× moles × 60.08 g/mol = 1.0152x10×g
So, a grain of sand weighs approximately 1.0152x10× grams.
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